GLACIERS  OF 
GLACIER  NATIONAL  PARK 


-  *•.  • 


;  . 


DEPARTMENT  OF  THE  INTERIOR 
OFFICE  OF  THE  SECRETARY 
1914 


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Z.T. 


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JK  /r  I  *  \  ' 

OL 

way 

GLACIERS  OF  GLACIER  NATIONAL  PARK.1 

By  Wm.  C.  Alden,  U.  S.  Geological  Survey. 


INTRODUCTION. 

Glacier  National  Park  derives  its  name  and  much  of  its  interest 
from  the  presence  of  many  small  glaciers.  Very  much  of  the  grandeur 
of  its  wonderful  Alpine  scenery,  the  final  sculpturing  of  the  great 
mountain  valleys  and  of  the  amphitheaters  at  their  heads,  and  the 
production  of  the  basins  of  its  many  beautiful  lakes  are  due  to  the 
action  of  the  more  extended  glaciers  of  the  past. 

There  are  in  the  park  about  90  small  glaciers  ranging  in  size  from 
Blackfeet  Glacier,  with  its  3  square  miles  of  ice,  down  to  masses  but  a 
few  acres  in  extent  Vet  exhibiting  the  characteristics  of  true  glaciers. 
The  most  easily  accessible  of  these  from  the  beaten  trails  are  the 
Blackfeet  and  Sperry  Glaciers  and  the  small  glaciers  at  Iceberg  Lake 
and  at  Ahern  Pass.  Some  of  the  others  can  be  reached  bv  tourists 
who  are  willing  to  undergo  the  exertions  of  mountain  climbing. 
Among  these  are  Grinnell,  Chaney,  Shepard,  Vulture,  and  Carter 
Glaciers,  and  one  or  two  at  Brown  Pass.  (See  map  facing  page  17.) 

After  examining  these  features  one  can  easily  picture  to  himself,  as 
he  looks  down  the  valleys,  the  great  rivers  of  ice  which  in  ages  past 
cascaded  from  the  cliffs  below  the  upper  cirques,  converged  as 
tributaries  from  the  many  branch  valleys,  and  united  in  great  trunk 
glaciers.  In  imagination  he  can  see  these  great  glaciers  many 
hundreds  of  feet  in  depth  filling  the  great  mountain  valleys  from  side 
to  side,  and  deploying  thence  upon  the  bordering  plains.  He  seems 
to  see  these  mighty  engines  plucking  away  the  rock  ribs  of  the  moun¬ 
tains,  smoothing,  grinding,  and  polishing  the  irregularities  and  sweeping 
away  the  debris  to  be  spread  on  the  plains  below.  These  glaciers 
developed  and  extended  three  times  and,  after  each  development, 
the  congealed  masses  melted  away  on  the  return  of  milder  climatic 
conditions,  until  at  length  only  the  small  cliff  glaciers  of  the  present 

1  The  descriptions  of  the  glaciers  and  the  discussion  of  the  glacial  phenomena  presented  in  this  paper  are 
based  upon  studies  by  the  writer,  made  during  the  summers  of  1911,  1912,  and  1913  for  the  United  States 
Geological  Survey,  in  and  adjacent  to  the  park.  He  was  assisted  in  1911  by  J.  Elmer  Thomas;  in  1912  by 
Eugene  Stebinger,  and  in  1913  by  Clifton  S.  Corbett.  Not  all  of  the  pricipal  glaciers  have  been  examined 
and  much  of  the  area  of  the  park  remains  to  be  covered  by  the  geological  survey.  The  presentation  in  this 
paper  is  thus  only  preliminary  in  character  and  is  intended  rather  as  a  popular  than  a  technical  discussion. 

For  further  treatment  of  the  physiographic  development  of  the  region  one  should  refer  to  the  companion 
pamphlet  issued  by  the  Department  of  the  Interior,  entitled  “  Origin  of  the  scenic  features  of  Glacier  National 
Park,  Montana,”  by  M.  R.  Campbell.  This  publication  may  be  purchased  from  the  Superintendent  of 
Documents,  Government  Printing  Office,  Washington,  D.  C.,  for  15  cents. 


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GLACIERS  OF  GLACIER  NATIONAL  PARK. 


day  are  left  lurking  in  the  protected  recesses  at  the  heads  of  the  capa¬ 
cious  valleys. 

Many  of  the  rock-walled  amphitheaters  are  no  longer  occupied  by 
ice,  but  from  all  there  issue  streams  fed  by  the  melting  snow  or  ice. 
These  plunge  over  the  cliffs  in  beautiful  foaming  cascades  and  rush 
on  down  the  mountain  gorges.  The  melting  glaciers  left  many 
inclosed  basins  large  and  small,  and  in  these  the  waters  rest  a  while 
and  mirror  in  their  crystal  depths  the  dark  green  of  the  surrounding 
forests,  the  rich  colors  of  the  rugged  mountain  walls,  and  the  deep 
blue  of  the  cloud-flecked  sky.  On  again  from  lake  to  lake  the  waters 
flow  and  finally  start  down  their  long  courses  to  the  sea  to  merge  at 
length  with  the  chill  waters  of  Hudson  Bay,  the  balmy  tides  of  the 
Gulf  of  Mexico,  or  the  rolling  billows  of  the  Pacific. 

Compared  in  size  with  the  great  glaciers  of  Alaska  the  glaciers  of 
Glacier  National  Park  are  insignificant.  They  are  even  surpassed 
in  size  by  those  of  the  Alps,  of  the  Canadian  Rockies,  and  of  Mount 
Rainier,  Washington.  They  are,  however,  though  small,  among  the 
best  examples  of  this  interesting  type  of  phenomena  now  existing  in 
the  United  States.  They  have  also  a  splendid  setting  in  magnificent 
Alpine  scenery,  unsurpassed  hi  grandeur  anywhere.  Hidden  away 
in  the  recesses  of  the  mighty  mountain  ranges  these  rare  and  won¬ 
derful  features  form  a  climax  to  many  of  the  interesting  trips  open 
to  the  tourist. 

BLACKFEET  GLACIER. 

General  relations. — The  largest  glacier  of  the  park,  one  of  the  most 
readily  accessible,  and  one  exhibiting  hi  fine  development  most  of  the 
features  particularly  characterizing  glaciers  is  the  Blackfeet 1  (title- 
page  and  fig.  13,  p.  24). 

From  Gunsiglit  Camp,  an  easy  trail  leads  southward  about  1  mile, 
with  an  ascent  of  about  500  feet,  to  the  foot  of  the  main  lobe  of  the 
western  part  of  the  glacier.  Climbing  the  morainal  embankment 
which  obstructs  the  view  one  looks  out  on  a  scene  of  surpassing 
interest  and  grandeur.  The  distance  across  the  glacier  on  a  nearly 
east-west  line,  is  3.2  miles;  the  maximum  extent  southward  from  the 
front  of  the  eastern  lobe  to  the  crest  of  the  snow-covered  Continental 
Divide  on  Blackfoot  Mountain  is  1.6  miles;  the  distance  from  the 
front  of  the  western  lobe  to  the  divide  southeast  of  Jackson  Mountain 
is  nearly  the  same ;  the  approximate  area  of  the  entire  mass  H3  square 
miles.  Lying  in  a  depression  in  the  mountain  slope,  having  a  greater 
extent  laterally  than  in  the  direction  of  movement,  and  having  no 
lobate  extension  down  the  valley,  it  is  what  is  known  as  a  cliff  glacier. 

i  In  an  article  in  the  Scientific  American  Supplement,  Sept.  23,  1899,  George  B.  Grinnell  states  that  in 
1891  he  took  to  the  head  of  St.  Mary  River  the  first  party  that  had  ever  visited  it  so  far  as  known.  In  1895 
in  company  with  a  Government  commission  he  again  visited  the  head  of  the  valley.  In  1897,  in  company 
with  J.  B.  Monroe,  he  climbed  Jackson  Mountain,  and  in  1898  he  ascended  Blackfoot  Mountain  and  from 
it  beheld  the  glacier  to  the  south  which  had  been  seen  in  1883  by  Prof.  Raphael  Pumpelly  on  a  trip  across 
Cut  Bank  Pass  and  which  since  that  time  has  been  known  as  Pumpelly  Glacier. 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


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Banked  against  the  upper  mountain  slopes  is  the  snow  field,  or 
neve,  from  which  the  glacier  originates.  Here  what  is  left  of  the  snows 
of  many*  winters  has  become  compacted  and  changed  to  granular  ice. 
When  such  ice  accumulates  to  a  sufficient  thickness  internal  move¬ 
ment  begins.  Such  moving  ice  constitutes  a  glacier.  High  up  on 
the  slopes  there  may  be  seen,  in  places,  a  line  of  crevasses  which 
marks  a  break  between  the  moving  ice  and  the  stationary  part  of 
the  neve.  Such  a  crevasse  is  called  the  “  bergschrund  ”  by  the 
Germans.  The  mam  or  eastern  part  of  the  glacier  nearly  fills  the 
upper  cirque  extending  almost  to  the  crest  of  the  cliff  at  the  head  of 
the  valley  southwest  of  Citadel  Mountain.  Beneath  the  western  part 
of  the  glacier  the  slope  nearly  coincides  with  the  inclination  of  the 
rock  and  there  is  no  marked  break  forming  a  cliff. 

Moving  down  this  slope,  the  ice  of  the  western  part  of  the  glacier 
gathers  in  from  all  sides  to  a  central  stream.  The  lower  0.7  of  a  mile 
of  its  extent  is  thus  contracted  to  a  narrow  lobe  about  1 ,600  feet  in 
width.  This  part  is  easily  accessible  to  the  tourist  and  here  may 
be  observed  most  of  the  typical  characteristics  of  alpine  glaciation. 
7’  Moraines. — Along  the  front  of  the  glacier  throughout  nearly  its 
whole  extent  is  a  great  embankment  or  moraine  of  clay  and  bowlders 
which  was  formed  by  the  piling  up  of  rock  debris  carried  forward  by 
the  moving  ice.  The  greater  part  of  such  material,  which  is  known 
as  drift,  is  embedded  in  the  lower  part  of  the  ice  when  being  trans¬ 
ported,  but  a  smaller  part  is  borne  upon  its  surface,  having  fallen 
from  the  mountain  slopes.  When  released  by  melting  at  the  glacial 
front  the  drift  accumulates  and  may  be  crowded  up  into  a  ridge. 
Much  of  the  morainal  material  piled  up  along  the  front  of  the  Black- 
feet  Glacier  probably  accumulated  some  time  ago  when  the  ice  was 
thicker  and  somewhat  more  extensive.  A  person  standing  on  the 
moraine  where  it  is  most  readily  accessible  from  the  trail  sees  the 
main  lobe  of  the  western  part  of  the  glacier  extending  down  between 
two  great  morainal  embankments.  The  glacier  thins  to  a  frontal 
margin  at  an  elevation  of  about  5,725  feet  above  sea  level.  The 
moraines,  however,  continue  some  distance  farther  down  the  slope 
and  there  they  curve  together  and  join  in  one  continuous  loop,  show¬ 
ing  that  at  some  earlier  date  this  lobe  had  a  somewhat  greater  exten¬ 
sion.  The  distance  from  the  end  of  the  morainal  loop  to  the  front  of 
the  ice  was  not  measured,  but  it  is  estimated  as  about  1,000  feet. 
Across  the  end  of  the  loop  trees  are  growing,  but  nearer  the  ice  there 
is  no  vegetation  and  the  bare  slopes  are  very  steep  and  in  places 
even  precipitous  as  the  result  of  slumping  and  sliding  of  the  clay  and 
bowlders.  The  moraine  ranges  in  height  from  20  to  100  feet  with  an 
uneven,  ridged  crest  varying  from  a  few  feet  to  a  few  yards  hi  width,  so 
that  it  is  a  striking  topographic  feature.  For  some  distance  from  the 
lower  end  of  the  ice  lobe  the  northwest  margin  has  been  melted  back 
50  to  100  yards,  from  the  foot  of  the  inner  slope  of  the  moraine,  expos- 


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GLACIERS  OF  GLACIER  NATIONAL  PARK. 


ing  the  bare,  smoothly  polished,  and  striated  ledges  of  rock  over 
which  the  ice  formerly  extended.  Farther  west  up  the  slope  the  thin 
ice  extends  to  the  foot  of  the  moraine.  On  the  east  side  of  the  lobe 
the  ice  extends  to  the  foot  of  the  moraine  but  the  crest  of  the  latter 
towers  high  above  it. 

Movement. — That  the  ice  is  not  stagnant  but  moving  slowly  forward 
may  be  easily  demonstrated.  Opposite  the  sharp  curve  in  the  moraine 
at  about  6,350  feet  above  tide  there  is  a  change  in  the  slope.  Looking 
into  a  low  ice  cave  at  this  place  one  can  see  far  under  the  glacier. 
Here  the  ice  after  passing  the  crest  of  the  ledge  extends  free  a  few 
feet  above  the  rock  over  an  area  of  many  square  rods  before  breaking 
down.  An  iron  spike  set  in  the  ice  at  this  place  on  August  19,  1913, 
showed  a  movement  of  3|  inches  in  the  first  24  hours,  of  three-eighths 
inch  in  the  next  5  hours,  and  of  3|  inches  in  the  succeeding  25  hours 
and  25  minutes.  This  gives  an  advance  of  7  inches  in  54  hours  and 
25  minutes. 

Owing  to  the  steepening  of  the  slope  at  this  place  the  ice  is  much 
crevassed.  Some  distance  farther  up  the  slope  is  another  broad 
zone  hi  which  the  ice  is  much  broken  by  crevasses.  A  second  spike 
set  in  the  ice  wall  of  a  cavity  at  a  point  N.  85°  W.  of  the  peak  of 
Jackson  Mountain  and  about  6,725  feet  above  tide  near  the  lower 
border  of  the  upper  crevassed  zone,  showed  an  advance  of  1J  inches 
hi  24  hours,  and  in  the  succeeding  30  minutes  an  additional  advance 
of  one-eiglitli  inch,  the  time  behig  in  the  middle  of  a  warm,  bright 
day. 

On  August  21,  a  marked  pebble  was  set  in  the  ice  at  a  point  hi 
front  of  the  glacier  N.  75°  E.  of  the  peak  of  Jackson  Mountain  and 
six-tenths  of  a  mile  northeast  of  the  6,879-foot  bench  mark.  The  ice 
at  this  pohit  advanced  seven-eighths  inch  in  4f  hours  during  the  warm 
part  of  a  warm  day. 

This  is  a  crude  method  of  measuring  the  rate  of  movement,  and  the 
results  can  not  be  regarded  as  a  true  index  of  the  rate  hi  all  parts  of 
the  glacier.  No  attempt  has  yet  been  made  to  obtahi  accurate 
measurements  of  the  movement  in  this  or  any  other  glacier  within 
the  park,  and  no  estimate  of  the  total  yearly  advance  can  be  made 
from  measurements  as  few  and  so  crude  as  these.  The  rate  of  glacial 
movement  varies  greatly  with  temperature  and  other  climatic  condi¬ 
tions,  being  more  rapid  on  warm  moist  days  than  on  cold  and  dry 
days.1 

Crevasses  and  ice  cascades. — Ice  has  little  elasticity,  so  that  crevasses 
are  produced  in  the  surface  of  a  glacier  by  tension  at  places  beneath 
which  are  considerable  irregularities  or  steepenings  of  the  rock  slope 
down  which  the  ice  is  moving.  As  the  broken  ice  moves  slowly  forward 


1  The  rates  of  average  daily  movement  of  glaciers  in  the  Canadian  Rockies  and  Selkirks  range  from  2 
to  20  inches,  of  the  great  Alaskan  glaciers  1  to  several  feet,  as  much  as  7  feet  on  Muir  Glacier.  In  the  Swiss 
Alps  the  rates  range  from  1  or  2  inches  to  4  feet  or  more  per  day. 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


7 


a  succession  of  fractures  constantly  takes  place  in  the  same  relative 
positions.  There  is  a  regular  cycle  in  the  development  of  crevasses 
which  is  well  illustrated  in  the  upper  crevassed  zone  on  the  west¬ 
ern  part  of  Blackfeet  Glacier  (title-page).  In  the  upper  part  of  the 
central  belt  the  cracks  appear;  farther  down  the  widening  of  the 
cracks  by  melting  breaks  the  surface  into  flat-topped  tables.  As  the 
crevasses  gradually  widen  the  intervening  tables  narrow  until  they 
become  sharp-crested  ridges  where  one  can  scarcely  find  footing.  Fol¬ 
lowing  this  the  sharp  ridges  may  be  broken  into  pinnacles  or  seracs, 
such  as  may  be  seen  at  one  place  near  the  ice  front  south  of  Citadel 
Mountain.  Finally  the  ridges  are  lowered  by  the  melting  and  gradu¬ 
ally  disappear.  With  the  closing  of  the  crevasses  below,  the  surface  of 
the  glacier  thus  becomes  again  smooth  and  passable.  Crevasses  are  also 
sometimes  healed  by  being  filled  with  snow  or  by  the  freezing  of  water 
which  may  accumulate  in  them  when  the  bottoms  are  tightly  closed. 
From  the  latter  result  the  ice  dikes  seen  on  some  of  the  other  glaciers. 

These  crevasses  are  dangerous  pitfalls  in  the  way  of  the  tourist, 
even  when  not  treacherously  hidden  by  a  slight  covering  of  snow. 
With  competent  guides  and  care,  however,  the  less  fractured  parts  of 
the  glacier  may  be  traversed  in  safety. 

At  many  points  on  the  higher  slopes  the  snow  and  ice  may  be  seen 
cascading  over  the  ledges.  Here  the  ice  is  greatly  crevassed  and 
broken  and  great  masses  stand  ready  to  fall,  especially  on  warm  days. 
Such  cascades,  though  very  attractive,  are  dangerous  to  approach. 
On  the  slope  of  Blackfoot  Mountain  (fig.  13,  p.  24),  where  a  great 
ledge  intervenes,  the  continuity  of  the  cascade  is  broken  for  some 
distance  by  a  cliff  of  bare  rock,  above  which  rises  a  cliff  of  ice.  Here 
the  ice,  which  is  pushed  forward  above  the  cliff,  may  break  off  and 
drop  to  the  glacier  below,  there  to  be  welded  by  refreezing  into  the 
continuous  sheet. 

Structure. — The  ice  composing  a  glacier  is  generally  stratified  in 
layers  as  a  result  of  the  conditions  of  original  deposition.  This  struc¬ 
ture  may  be  indicated  by  more  or  less  definite  dirt  zones  extending  in 
parallel  curving  lines  across  the  surface  of  the  glaciers.  As  the  layer 
of  snow  which  accumulates  during  one  winter  is  gradually  thinned  or 
melted  away  during  the  succeeding  summer,  dust  and  small  rock 
fragments  which  have  fallen  upon  it  become  concentrated  in  a  thin 
but  fairly  definite  layer.  This  is  later  buried  beneath  the  clean 
snows  of  the  following  winter.  When  compacted  to  glacier  ice,  there¬ 
fore,  there  are  apt  to  be  thin  layers  of  somewhat  dirty  ice  alternating 
with  thicker  clean  layers.  In  places  where  the  surface  of  the  snow 
docs  not  become  soiled  by  rock  debris,  melting  may  cause  the  forma¬ 
tion  of  a  crust  of  nearly  clear  ice  which,  when  buried  by  later  snows, 
appears  as  a  blue  band.  The  thicker  intervening  layers  appear  white 
because  the  unfilled  air  spaces  between  the  ice  granules  permit  reflec¬ 
tion  of  light  from  the  myriad  surfaces.  The  beautiful  banded 


8 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


structure  of  alternating  blue  and  white  ice  may  be  seen  in  the  sides 
of  the  crevasses.  As  the  glacier  is  thinned  by  melting,  these  layers 
outcrop  as  zones  in  the  frontal  slope.  They  correspond,  in  a  way,  to 
the  annular  rings  in  the  growth  of  a  tree. 

Drainage. — During  the  cool  nights  and  early  mornings  there  is 
little  sound  of  water  on  a  glacier,  but  as  the  day  warms  little  rivulets 
begin  to  flow  on  the  surface  of  the  ice;  where  there  is  much  crevassing 
the  water  finds  its  way  quickly  to  the  base  of  the  glacier,  and  there  it 
may  be  heard  rushing  down  the  slope.  From  the  front  of  the  ice 
there  flow  rushing  streams  white  with  silt  from  the  rock  ground  fine 
beneath  the  glacier,  the  “ gletschermilch ”  of  the  Germans.  The  main 
or  eastern  part  of  Blackfeet  Glacier  is  somewhat  less  crevassed  and 
more  water  flows  in  rivulets  upon  the  ice.  These  unite  to  form 
streams  a  foot  or  two  in  width,  but  of  high  velocity,  since  the  surface 
of  the  glacier  has  toward  the  front  a  15°  slope.  The  sharply  sinuous 
channels  cut  in  the  ice  reach,  in  places,  depths  of  20  to  35  feet.  At 
one  point  a  stream  was  seen  plunging  down  a  vertical  well,  or  moulin, 
to  join  the  subglacial  flow.  The  depth  of  such  a  hole  might  be 
measured  to  ascertain  the  thickness  of  the  ice. 

Worlc  of  the  glacier. — The  work  of  such  a  glacier  as  that  being 
described  is  manifested  in  the  production  of  the  cirque  or  amphitheater 
which  it  occupies,  in  the  abrasion  of  the  rock  floor  over  which  it 
moves,  and  in  the  deposits  resulting  from  the  drift  which  it  produces 
and  transports. 

The  greater  part  of  the  rock  composing  the  mountains  of  the  park  is 
stratified  in  layers,  mostly  thin,  but  ranging  in  thickness  from  a 
fraction  of  an  inch  to  30  feet  or  more.  The  strata  are  generally 
broken  at  frequent  intervals  by  cracks  or  joints,  and  water  percolating 
into  these  crevices  expands  on  freezing  and  forces  the  pieces  apart. 
Alternate  freezing  and  thawing  breaks  up  and  loosens  the  fragments 
ready  to  be  removed.  Many  fall  or  are  carried  down  from  the  cliffs 
and  upper  slopes  by  avalanches  of  snow.  Others  beneath  and 
behind  the  glaciers  become  frozen  in  the  moving  ice  and  are  plucked 
from  their  places  and  slowly  carried  away.  The  ice  always  advances 
and  never  retreats,  so  that  as  long  as  the  glacier  exists,  unless  it 
becomes  absolutely  stagnant,  material  is  continually  being  removed. 
A  glacier  may  thus  be  said  to  gnaw  continually  at  the  slope  and  eat 
its  way  back  into  the  mountain. 

Some  geologists  maintain  that  the  breaking  up  of  the  rock  and  the 
plucking  away  of  the  loosened  fragments  is  particularly  facihtated  by 
changes  in  temperature  in  the  air  and  the  water  admitted  by  the 
yawning  bergschrund  which  is  so  often  seen  in  the  neve  at  the  back 
of  the  glacier.  Continued  sapping  steepens  the  walls  until  the  great 
amphitheaters  or  cirques  are  produced.  The  Blackfeet  Glacier  does 
not  occupy  such  a  deep  and  symmetrical  cirque  as  is  seen  at  many 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


9 


other  places  in  the  park.  It  is  probable,  however,  that  this  is  still 
being  extended  back  into  the  mountain  slope. 

Only  a  relatively  small  amount  of  rock  debris  falls  from  the  upper 
mountain  slopes  onto  the  Blackfeet  Glacier,  and  there  is  little  or  no 
drift  seen  embedded  in  the  ice  exposed  in  the  sides  of  the  crevasses, 
neither  is  any  being  carried  by  the  surficial  streams.  Looking  into 
caverns  under  the  ice,  one  sees  here  and  there  pebbles  and  bowlders 
at  or  in  the  bottom  of  the  ice,  and  the  undersurface  is  coated  with  a 
thin  layer  of  mud,  the  product  of  the  grinding  of  the  fragments  and 
of  the  rock  bed  beneath  the  glacier.  One  sees  also  the  smoothed, 
polished,  and  striated  rock  surface  extending  back  beneath  the  base 
of  the  moving  ice.  A  glacial  quarry  was  observed  in  the  upper  part 
of  the  bared  space  between  the  northwest  margin  of  the  Blackfeet 
Glacier  and  the  moraine.  Here  the  ice  has  evidently  plucked  loosened 
blocks  from  the  exposed  edges  of  the  strata  as  quarrymen  remove 
layer  from  layer  in  the  process  called  stoping.  Many  blocks  derived 
in  this  way  are  found  incorporated  in  the  morainal  embankments. 
Some  of  the  blocks  are  but  little  worn,  as  though  transported  on  the 
surface  of  the  ice,  but  most  of  them  are  subangular  with  polished  and 
striated  facets,  showing  the  effects  of  abrasion  beneath  the  glacier. 
Much  of  the  morainal  material  is  fine  rock  flour.  The  whole  con¬ 
stitutes  a  heterogeneous  deposit  of  unassorted  glacial  till.  Sharp 
morainal  embankments  border  nearly  the  whole  frontal  margin  of 
the  Blackfeet  Glacier  (fig.  13,  p.  24). 

Former  extent  of  the  glacier. — The  marginal  lobes  of  the  main  eastern 
part  of  this  glacier,  like  the  western  lobe,  are  somewhat  shrunken 
from  their  moraines,  an  indication  that  some  tune  ago  the  ice  had  a 
greater  extension. 

On  the  slope  between  Gunsight  Camp  and  the  glacier  the  surface 
of  the  limestone  is  in  most  places  somewhat  roughened  as  a  result 
of  etching  by  solution  by  the  water  flowing  over  it.  In  places, 
however,  the  surface  is  smooth,  polished,  and  scratched  the  same  as 
the  rock  surfaces  within  the  moraines.  This  indicates  that  at  some 
time  the  glacier  extended  beyond  the  limits  now  marked  by  the  mo¬ 
raines.  Similar  glaciated  surfaces  are  found  far  down  St.  Mary 
Valley,  and  the  valley  bottom  and  lower  side  slopes  carry  glacial 
drift  quite  to  the  international  boundary,  a  distance  of  38  miles  from 
the  divide  at  Blackfoot  Mountain.  Such  drift  extends  up  the  slope 
east  of  Lower  St.  Mary  Lake  nearly  to  5,800  feet  above  tide;  i.  e., 
1,300  feet  above  the  lake.  Drift  was  also  found  on  the  slope  of 
Singlcshot  Mountain  west  of  Upper  St.  Mary  up  to  an  elevation  about 
1,200  feet  above  the  lake.  Moreover,  that  part  of  St.  Mary  Valley 
within  the  mountains  has  not  the  sharply  cut  V-shaped  transverse 
profile  of  a  stream-cut  mountain  gorge,  but  has  the  broadly  rounded 
U-shaped  profile  typical  of  a  glaciated  valley.  Tributary  to  St. 

36592°— 14 - 2 


10 


GLACIERS  OF  GLACIER  XATIOXAL  PARK. 


Mary  \  alley  above  the  lower  lake  are  more  than  25  cirques,  which 
formerly  contained  glaciers.  From  such  evidence  it  is  apparent  that 
the  whole  St.  Mary  Valley  as  far  down  as  the  international  boundary 
was  once  occupied  by  a  great  glacier,  of  which  Blackfeet  Glacier  and 
17  other  smaller  glaciers  remain  as  the  only  representatives  in  this 
part  of  the  park.  (See  map  facing  page  32.)  The  contours  of  the 
valley  indicate  that  the  great  St.  Mary  Glacier  must  have  had  a 
thickness  of  2,000  to  2,500  feet  where  is  now  Upper  St.  Mary  Lake. 

Glacial  modification  of  St.  Mary  Valley. — Figure  1,  A  and  B,  which 
is  based  on  the  contours  of  Swiftcurrent  Valley,  illustrates  the  differ¬ 
ence  between  a  stream-cut  mountain  valley  and  the  same  valley  after 
it  has  been  subjected  to  vigorous  glaciation.  In  the  paper  by  Mr. 
M.  R.  Campbell  on  the  origin  of  the  scenic  features  of  the  park,  it  is 
pointed  out  that  the  formation  of  the  great  mountain  valleys  was 


A. 


B. 


Fig.  1. — A,  Sketch  of  stream-cut  valley;  B,  sketch  of  same  valley  after 

MODIFICATION  BY  GLACIATION. 


due  primarily  to  the  work  of  streams  which  cut  deeply  into  the  moun¬ 
tain  mass.  When  climatic  conditions  became  such  as  to  result  in 
the  vast  accumulation  of  snow  great  glaciers  developed  in  each  of 
the  mountain  valleys.  As  the  glaciers  gradually  extended  all  of  the 
loose  rock  debris  which  had  accumulated  on  the  lower  part  of  the 
slopes  and  at  their  feet  became  frozen  into  the  base  of  the  ice.  Par¬ 
tially  loosened  blocks  were  also  plucked  away  bodily  and  moved 
forward  down  the  valleys.  A  mass  of  ice  2,000  feet  in  thickness 
exerts  a  pressure  of  56  tons  per  square  foot  on  the  bed  upon  which  it 
rests.  The  rock-shod  ice  thus  became  in  effect  an  enormous  rasp, 
which  scored  and  polished  and  wore  away  all  the  minor  irregularities 
of  the  slopes  and  bottoms  of  the  valleys.  Such  enormous  masses 
of  moving  ice  do  not  adjust  themselves  to  the  sinuosities  and  irregu¬ 
larities  of  the  valleys  as  readily  as  does  water  in  its  liquid  state.  In 
consequence  of  this  and  of  the  enormous  weight  of  the  moving  mass, 
every  opposing  ledge  and  mountain  spur  were  subjected  to  vigorous 
abrasion;  the  valley  bottom  was  broadened  and  the  side  slopes  were 
steepened  until  the  whole  became  a  broad  open  trough. 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


11 


The  attitude  of  the  rock  strata  and  the  resistance  which  they 
offered  to  removal  as  a  consequence  of  differences  in  hardness  or  in 
massiveness  of  bedding  determined  in  some  degree  the  depths  to 
which  the  valley  was  deepened  in  various  parts.  Thus  a  particularly 
resistant  stratum,  such  as  the  massive  ledge  of  limestone  which  crosses 
St.  Mary  Valley  at  the  narrows  in  Upper  St.  Mary  Lake,  was  not 
worn  away  to  the  same  extent  as  were  the  softer  rocks  farther  down 
the  valley  or  the  thinner-bedded  rocks  above.  Broader  basins  were 
thus  developed  above  and  below  this  ledge,  and  when  the  ice  melted 
away  these  basins  were  filled  with  water,  forming  a  lake.  The  failure 
to  cut  as  broad  a  channel  through  the  limestone  ledge  caused  the 
constriction  or  narrows  in  Upper  St.  Mary  Lake.  In  some  of  the 
other  valleys,  such  as  Swiftcurrent  Valley,  a  lake  was  formed  above 
the  ledge,  but  no  channel  was  cut  through,  so  that  the  escaping  waters 
plunge  in  a  foaming  cascade  over  the  obstruction  to  the  valley  below. 
Moraines  and  other  deposits  of  drift  were  left  on  the  melting  of  the 
great  valley  glaciers,  and  in  some  places  lakes,  such  as  Bowman  Lake 
and  Quartz  Lake,  are  due,  in  part  at  least,  to  the  blocking  of  the 
valleys  by  such  accumulations  of  drift. 

HARRISON  GLACIER. 

One  of  the  interesting  trips  from  Gunsight  camp  is  southwestward 
up  the  smooth,  snow-covered  surface  of  the  upper  western  part  of  the 
Blackfeet  Glacier  to  the  crest  of  the  Continental  Divide  in  the  notch 
southeast  of  Jackson  Mountain.  Looking  westward  from  this  point 
one  gets  a  magnificent  view  of  the  cascading  lobes  of  Harrison  Glacier 
(fig.  2).  The  main  glacier,  which  lies  high  in  the  upper  northern  part 
of  the  great  cirque  at  the  head  of  Harrison  Creek,  is  seven-tenths  of 
a  mile  wide  from  east  to  west  and  nearly  a  mile  long  from  north  to 
south.  From  this  a  series  of  ice  lobes  spill  over  and  cascade  down 
the  steep  slope  to  benches  in  the  great  cirque  wall.  Of  these  the  one 
nearest  the  observer  and  the  one  farthest  away  appear  to  extend  to 
well-marked  moraines,  the  one  near  by  does  not  reach  the  highest 
and  outermost  of  the  ridges,  but  ridged  drift  is  spread  over  the  space 
between  the  ridge  and  the  ice  front.  The  front  of  the  fourth  is  some 
distance  back  from  the  end  moraine,  from  which  two  finely  developed 
laterals  extend  up  the  slope.  The  fifth  lobe  breaks  off  at  the  top  of 
a  cliff  over  which  its  morainal  material  is  pushed. 

SPERRY  GLACIER. 

General  relations. — High  up  in  the  upper  cirque  at  the  head  of 
Avalanche  Basin  lies  Sperry  Glacier 1  (fig.  12,p.24).  This  is  next  in  size 
to  Blackfeet  Glacier,  having  a  maximum  width  at  the  front — i.  e.,  from 

1  In  January,  1896,  there  was  published  in  Appalachia  (Vol.  VIII,  pp.  57-69)  an  article  by  Lyman  B. 
Sperry  on  Avalanche  Basin,  Montana  Rockies,  in  which  he  described  explorations  of  this  basin  made  in 
May  and  July,  1895,  by  a  party  of  which  he  was  a  member.  An  effort  was  made  at  this  time  to  reach  the 
upper  cirque  and  find  the  source  of  the  waters  which  were  seen  to  be  milky  with  glacial  silt.  It  was  not, 
however,  until  1896  that  Dr.  Sperry  succeeded  in  reaching  the  glacier  which  now  bears  his  name.  (See 
Glaciers  in  the  Montana  Rockies,  by  L.  W.  Chaney,  jr.,  Science,  new  ser.,  Vol.  IV,  pp.  761-762, 1896.) 


12 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


Fig.  2. — Harrison  Glacier,  showing  the  cascading  frontal  lobes. 

Photograph  by  W.  C.  Alden. 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


13 


northeast  to  southwest — of  1^  miles — and  a  length — i.  e.,  from  north¬ 
west  to  southeast — of  about  1  mile.  Its  area  is  estimated  as  about  1 
square  mile.  The  great  cirque  at  the  head  of  Snyder  Creek  between 
Edwards  Mountain  on  the  south  and  Mount  Brown  on  the  north  was 
excavated  so  far  back  into  the  mountain  mass  that  the  upper  part  of 
the  divide  between  Snyder  Valley  and  Avalanche  Basin  was  cut 
away,  leaving  a  broad  notch  between  Edwards  Mountain  and  the 
small  pyramidal  peak  known  as  Little  Matterhorn.  Through  this 
col  some  of  the  water  from  the  eastern  part  of  Sperry  Glacier  goes 
to  Snyder  Creek.  A  similar  notch  was  also  developed  between 
Edwards  Mountain  and  Gunsiglit  Mountain.  It  is  through  this 
latter  notch  that  the  trail  climbs  from  the  creek  at  the  crossing  below 


Fig.  3. — Moat  at  east  side  op  Sperry  Glacier,  showing  stratification  in 

THE  ICE  WALL  ON  THE  RIGHT. 

Photograph  by  W.  C.  Alden. 

Sperry  Camp,  about  6,200  feet  above  tide,  to  the  southwest  side  of 
the  glacier  at  7,700  ±  feet  above  tide. 

The  surface  of  the  ice  is  for  the  most  part  smooth  and  not  crevassed 
and  may  be  crossed  in  any  direction.  With  care  one  may  also  de¬ 
scend  the  slope  to  the  frontal  margin.  At  the  southwest  side,  the 
front  is  about  450  feet  lower  than  the  top  of  the  iron  ladder.  It  is 
at  and  near  the  front  of  the  ice  that  the  most  interesting  phenomena 
arc  to  be  observed. 

Structure. — In  the  front  slope  soiled  zones  mark  the  outcropping  of 
the  dirty  surfaces  of  successive  ice  strata,  each  the  residuum  of  one 
or  more  year’s  snowfall.  Other  than  this  the  surface  of  the  glacier  is 
almost  entirely  clean  of  debris  excepting  on  the  lower  part  of  the 
frontal  slopes  immediately  adjacent  to  the  ice  margin  where  there  is 
a  scattering  of  pebbles  and  bowlders  with  a  little  clay.  The  stratifi- 


14 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


cation  may  also  be  seen  in  the  sides  of  the  few  open  crevasses.  The 
best  view,  however,  of  the  bedded  structure  of  the  glacier  is  to  be 
had  where  the  east  side  of  the  glacier  rounds  a  salient  of  the  cirque 
wall  at  a  point  about  two-fifths  of  a  mile  south-southeast  of  the  front 


Fig.  4. — Sperry  Glacier,  bergschrund  on  slope  of 
Edwards  Mountain. 

Photograph  by  W.  C.  Alden. 

of  the  most  easterly  marginal  lobe  of  the  glacier.  On  the  northwest 
side  of  the  point  of  the  salient  instead  of  the  ice  crowding  against  the 
rock  slope  there  is  a  great  chasm,  or  moat  (fig.  3),  one  side  of  which 
is  formed  by  the  rock  wall.  The  other  is  a  smooth,  curving  wall 
of  stratified  ice,  150  feet  or  more  in  height.  This  moat  is  probably 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


15 


due,  in  part,  to  the  fact  that  the  ice  passing  the  rock  salient  does  not  at 
once  spread  laterally  after  passing  the  point.  The  lower  part  of  the 
cliff  thus  exposed  is  warmed  by  the  afternoon  sun  and  radiates  a  cer¬ 
tain  amount  of  heat  which,  melting  the  ice,  tends  to  prevent  its  closing 
up  the  moat  until  it  has  passed  on  some  distance  around  the  point 
or  may  even  actually  enlarge  it.  The  water  resulting  from  the  melting 
escapes  laterally  beneath  the  glacier  so  that  the  moat,  at  least  when 
visited  by  the  writer  in  August,  1913,  contained  no  stream  or  ponds. 

Ice  caves  and  glacial  movement. — In  the  upper  part  of  the  neve  on 
the  slope  of  Edwards  Mountain  a  bergschrund  (fig.  4)  yawns  as  the 
result  of  the  ice  moving  away  from  the  mountain  slope.  At  several 
points  along  the  front  of  the  glacier  there  are  small  caverns.  Instead 
of  breaking  down  immediately  after  passing  the  highest  part  of  a 
ledge,  the  ice  projects  forward  as  an  arch  fluted  in  correspondence 
with  the  inequalities  of  the  ledge  surface.  One  such  ice  cave 
was  seen  into  which  a  person  could  walk  a  distance  of  50  or  60 
feet  from  the  entrance,  and  probably  one  could  proceed  an  equal  dis¬ 
tance  farther  if  disposed  to  crawl  on  his  hands  and  knees  on  the  wet 
rock.  In  these  caverns  the  fact  that  the  ice  is  really  in  motion  may 
readily  be  demonstrated.  Markers  were  placed  in  the  ice  walls  and 
upon  the  ledges,  and  the  distance  between  the  marker  in  the  ice  and 
that  on  the  ledge  was  carefully  measured  with  the  following  results: 

Movement  of  ice  in  ice  cave  No.  1,  at  point  S.  37°  E.  of  Little  Matterhorn. — 12.15  p.  m., 
August  15,  to  11.15  a.  m.,  August  16;  advance  of  one-fourth  inch  in  23  hours.  11.30 
a.  m.,  August  16,  to  10.25  a.  m.,  August  17;  advance  of  one-half  inch  in  24  hours.  10.30 
a.  m.,  August  17,  to  11.15  a.  m.,  August  17,  advance  of  one-eighth  inch  in  45  minutes; 
11.15  a.  m  to  4  p.  m.,  advance  of  one-eighth  inch  in  4f  hours. 

Movement  of  ice  in  ice  cave  No.  2  at  point  S.  43°  E.  of  Little  Matterhorn. — Noon,  Au¬ 
gust  16,  to  noon,  August  17,  advance  of  one-half  inch  in  24  hours. 

Movement  of  ice  in  ice  cave  No.  3,  west  side  of  middle  ice  lobe,  at  point  S.  87°  E.  of  Little 
Matterhorn. — 1.15  p.  m.,  August  16,  to  1.15  p.  in.,  August  17,  advance  of  three-fourths 
inch  in  24  hours. 

Movement  of  ice  in  ice  cave  No.  4  at  west  side  of  eastern  ice  lobe  at  point  S.  45°  E.  of 
Heavens  Peak. — 2.30  p.  m.,  August  16,  to  2.30  p.  m.,  August  17,  an  advance  of  about 
one-half  to  three-fourths  inch  in  24  hours;  markers  loosened  by  melting. 

The  measurements  have  not  been  continued  over  a  sufficiently  long 
period  to  warrant  basing  upon  them  an  estimate  of  the  average  daily 
or  total  yearly  advance.  The  measurements  made  in  cave  No.  1 
show  the  variations  in  the  rate  of  motion  due  to  difference  in  tempera¬ 
ture.  On  the  first  day,  August  15,  when  the  weather  was  cold  and 
blustering,  with  some  snow  falling,  an  advance  of  but  one-fourth  inch 
was  noted.  During  the  following  24  hours  the  weather  became  bright 
and  warm,  there  was  much  melting  of  the  ice,  and  the  advance  noted 
then  was  one-half  inch. 

'  Moraines. — The  front  of  the  glacier  is  bordered  by  well-marked 
terminal  moraines.  These  are  sharp,  narrow,  and  uneven-crested 
embankments  20  to  50  feet  in  height,  composed  of  intermingled  clay, 


16 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


or  rock  flour,  pebbles,  and  bowlders.  Generally  there  is  an  interval 
of  a  few  rods  between  the  ice  and  the  mam  ridges,  showing  that  the 
glacial  margin  has  retreated  somewhat  since  the  formation  of  the  mo¬ 
raine.  The  foot  of  the  glacier,  for  the  most  part,  rests  on  nearly  bare 
rock,  but  in  one  place  it  appears  to  lie  on  top  of  a  morainal  accumula¬ 
tion  nearly  50  feet  hi  height  (fig.  5).  Here  one  sees  the  moraine  hi 
process  of  construction.  It  is  possible  that  the  drift  here  merely 
covers  the  margin  of  the  glacier  so  that  the  core  of  the  ridge  is  of  ice* 
The  southwest  half  of  the  glacier  is  underlain  by  banded  red  and 
white  quartzite  and  argillite,  while  the  floor  of  the  northeast  half  of 
the  cirque  is  composed  of  the  grayish  to  buff  limestone.  As  a  result 
the  southwest  half  of  the  terminal  moraine  is  composed  principally  of 


Fig.  5. — Moraine  at  front  of  Sperry  Glacier. 

Photograph  by  W.  C.  Alden. 

maroon-red  argillite  and  quartzite,  and  the  water  in  the  brooks  and 
morainah  ponds  is  reddish  from  the  silt  held  in  suspension.  The 
northeast  half  of  the  moraine,  on  the  contrary,  is  composed  mostly 
of  grayish  limestone,  and  the  water  of  the  ponds  and  streams  issuing 
here  is  white,  the  typical  “gletschermilch.” 

At  two  places  marginal  lobes  of  the  ice  project  forward  in  trougli- 
like  depressions  in  the  rock  floor  of  the  cirque.  Where  these  ice- 
tongues  occur  the  moraine  bends  sharply  and  extends  parallel  to  the 
sides  of  the  lobes  as  lateral  moraines.  These  laterals  are  connected 
in  a  large  loop  about  the  end  of  each  ice  lobe. 

A  short  distance  outside  the  inner  morainal  belt  is  one  of  earlier 
formation  disposed  hi  loops  indicating  that  the  ice  margin  was  for¬ 
merly  somewhat  more  lobate  than  at  present.  This  outer  moraine 
is  subdued  in  contour,  the  irregularities  of  crest  and  slope  having  been 


I 


11420' 


114  10' 


113' 50' 


113  40' 


113  30' 


113  20' 


GLACIERS  OF  GLACIER  NATIONAL  PARK.  17 

partially  washed  away,  and  is  covered  in  part  by  a  scanty  growth  of 
dwarfed  trees. 

y  Rock  scoring  and  plucking. — In  the  ice  caverns  the  observer  gets  an 
excellent  idea  of  the  abrasive  work  done  by  the  glacier.  The  surface 


Fig.  6. — Glaciated  groove  near  front  of  Sperry  Glacier. 

Photograph  by  W.  C.  Alden. 

of  the  bed  rock  is  beautifully  smoothed,  polished,  and  striated.  This 
surface  is  seen  to  extend  back  under  the  moving  ice  whose  under¬ 
surface  is  plastered  with  a  thin  coating  of  wet  mud  or  rock  flour,  and 
set  with  fragments  of  rock.  This  is  the  abrasive  material  with  which 
the  work  is  done.  There  seems  to  be  no  considerable  amount  of 
36592°— 14 - 3 


18 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


gravel  or  rock  fragments  in  the  base  of  the  ice,  as  removal  of  the  sub- 
surfieial  coating  shows  clear,  clean  ice  above.  Here  may  be  seen 
how  the  ice,  melting  under  pressure  against  inequalities  of  the  rock 
surface,  is  fluted  with  grooves  corresponding  to  those  irregularities, 
while  at  the  same  time  all  the  small  projections  are  being  worn  away. 

Not  only  does  the  surface  of  the  rock  floor  of  the  cirque  within  the 
moraines  show  the  effects  of  glaciation,  but  between  the  outer  moraine 
and  the  lip  of  the  cirque,  below  which  the  great  cliff  drops  to  form  the 
head  of  Avalanche  Basin,  the  rock  is  smoothed,  polished,  striated, 
and  grooved  in  a  remarkable  manner.  In  places  the  ice  has  been 
forced  along  more  or  less  tortuous  grooves,  which  were  probably  first 
worn  by  water  running  beneath  the  ice  (fig.  6). 

The  method  of  glacial  quarrying  known  as  plucking  is  also  well 
illustrated.  At  one  place  east  of  Little  Matterhorn  the  striated  floor 
is  cut  by  a  vertical  northeast-southwest  joint  face.  Beyond  this  a 
lower  level  was  in  process  of  being  developed  by  stoping  when  the 
ice  was  melted  away.  Some  great  blocks  of  rock  10  by  15  by  20  feet 
in  size  have  been  loosened  along  the  joints  and  moved  distances 
ranging  from  a  few  inches  to  several  feet.  Others  have  been  moved 
50  to  100  yards  or  more  and  left  stranded  between  the  quarry  face  and 
the  lip  of  the  upper  cirque.  Still  others,  doubtless,  were  forced  on 
over  the  cliff  to  be  dashed  in  fragments  on  the  ledges  below.  At  one 
point  the  opposed  faces  of  a  joint,  now  3  to  5  feet  apart,  are  striated 
in  a  direction  transverse  to  that  of  the  striae  of  the  main  ice  movement 
on  the  floor  above  as  though  the  basal  ice  had  squeezed  laterally  into 
the  crack  and  gradually  forced  the  block  on  the  northeast  away  from 
its  original  position.  One  joint  but  a  few  feet  back  from  the  crest 
of  the  cliff  at  the  head  of  Avalanche  Basin  has  been  broadened 
several  feet  to  a  considerable  depth.  Had  the  disrupting  action 
continued  but  a  little  farther  a  great  mass  of  the  upper  part  of  the 
cliff  would  have  been  tipped  over  into  the  great  cirque  below.  It  is 
largely  by  such  processes  of  glacial  plucking  or  stoping  that  the 
great  cirques  have  been  excavated.  It  seems  probable  that  only  a 
subordinate  amount  of  material  was  removed  by  abrasion  beneath 
the  great  rasp  formed  by  the  rock-shod  ice. 

Former  extent  of  the  glacier. — The  relations  are  such  that  there  can 
be  no  doubt  that  in  comparatively  recent  time,  geologically  speaking, 
though  thousands  of  years  ago,  Sperry  Glacier  not  only  occupied  the 
whole  of  the  upper  cirque  but  filled  Avalanche  Basin  and  was  con¬ 
fluent  with  a  great  glacier  in  the  canyon  of  McDonald  Creek  (see 
map  facing  p.  32). 

At  its  southwestern  end  the  terminal  moraine  is  near  the  crest  of 
the  cliff  at  the  head  of  Snyder  Creek.  Some  of  the  water  from  the 
western  part  of  the  glacier  flows  over  this  cliff.  The  trend  of  the 
striae  outside  the  moraine  also  indicates  that  some  of  the  ice  formerly 
passed  through  the  gap  between  Edwards  Mountain  and  Little  Matter- 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


19 


horn  and  joined  a  glacier  in  Snyder  Creek  Akalley.  It  is  also  probable 
that  some  of  the  ice  went  through  the  gaps  between  Edwards  Moun¬ 
tain  and  Gunsight  Mountain  to  a  glacier  in  Sprague  Creek  Valley. 

All  over  the  rock  shelf  on  which  stands  Sperry  Camp  and  on  the 
ledges  along  the  trail  to  Sperry  Glacier  there  is  a  fine  exhibition  of 
the  polishing  and  striating  action  of  the  glacier  which  formerly 
occupied  the  valley.  Striae  on  some  vertical  faces  beside  the  trail 
slope  steeply,  in  places  nearly  or  quite  vertically,  showing  how  the 
ice  descended  from  ledge  to  ledge. 


SWIFTCURRENT  GLACIERS. 


Grinnell  Glacier. — The  largest  of  the  glaciers  at  the  heads  of  tribu¬ 
taries  of  Swiftcurrent  Valley  is  the  Grinnell  Glacier,  so  named  in 
honor  of  Mr.  George  B.  Grinnell,  one  of  the  first  to  explore  these  moun¬ 
tains.  This  occupies  the  upper  cirque  on  the  north  side  of  Gould 
Mountain.  From  Sherburne  Lakes,  10  miles  distant,  the  white  and 
glistening  glacier  may  be  seen  nestling  at  the  foot  of  the  Garden 
Wall  in  the  cirque  between  Gould  and  Grinnell  Mountains.  While 
not  so  readily  accessible  as  some  of  the  other  glaciers  this  one  can  be 
reached  from  Many-Glacier  Camp  by  going  up  Cataract  Creek  trail 
along  the  west  shore  of  McDermott  Lake  and  then  climbing  up  and 
along  the  south  slope  of  Grinnell  Mountain  (figs.  7  and  8),  or  one  may 
get  a  fine  view  of  it  from  above  by  a  climb  from  Granite  Park  to  a 
notch  in  the  Garden  Wall. 

This  glacier  has  a  width  from  northwest  to  southeast  of  about  1§ 
miles  and  a  length  from  southwest  to  northeast  of  about  1  mile. 
Its  area  is  a  little  over  1  square  mile.  It  consists  of  a  neve-covered 
upper  part,  lying  on  an  upper  bench  in  the  western  part  of  the  cirque, 
and  the  main  glacier,  whose  lowest  point  is  not  far  from  the  crest 
of  the  cliff  which  rises  abruptly  nearly  1,000  feet  from  the  valley 
floor  above  Grinnell  Lake.  Through  most  of  its  lateral  extent  the 
upper  mass  of  ice  ends  at  the  crest  of  the  bare  rock  ledge  below  the 
upper  bench.  South  of  this,  however,  the  ice  cascades  over  the  ledge 
with  a  much  crevassed  surface  to  the  main  glacier  below.  From  the 
encircling  cliffs  the  ice  flow  converges  toward  the  lowest  point  in  the 
lip  of  the  cirque.  A  large  part  of  the  surface  is  crevassed,  showing 
that  the  ice  is  moving  down  over  an  uneven  bed,  and  nearly  the  whole 
surface  is  banded  with  the  soiled  zones  which  mark  the  outcropping 
of  the  ice  strata.  A  morainal  embankment,  consisting  of  narrow 
sharp-crested  ridges  of  drift  30  to  100  feet  in  height,  closely  borders 
the  ice  margin  on  the  east  and  north.  (Figs.  7,  8,  and  9.)  This  is  in 
part  lateral  and  in  part  a  terminal  moraine. 

In  a  little  niche  at  the  side  of  a  deep  notch  in  the  crest  of  the  Gar¬ 
den  Wall  back  of  Gould  Mountain,  a  thousand  feet  or  more  above  the 
main  glacier,  is  a  fine  example  of  a  cliff  glacier  (fig.  8).  This  glacier 
is  short  and  relatively  thick.  From  the  crest  of  the  rock  cliff  its 


20 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


nearly  vertical  face  of  glistening  stratified  ice  rises  100  feet  or  more 
to  the  smoothly  rounded,  snow-covered  crest  (fig.  10). 

On  the  north  side  of  Grinnell  Mountain  lies  another  small  glacier  on 
a  rock  shelf  at  the  top  of  a  1,500-foot  cliff.  This  is  in  view  of  tourists 


Fig.  7. — Gould  Mountain  and  Grinnell  Glacier. 

Morainal  ridge  at  left  and  in  foreground. 

Photograph  by  T.  W.  Stanton. 

traversing  the  trail  to  Swiftcurrent  Pass.  The  ice,  which  is  much 
crevassed,  extends  to  the  crest  of  the  cliff  in  places  and  dumps  some 
of  its  morainal  drift  into  the  abyss  below. 

In  the  next  cirque  north  of  Swiftcurrent  Pass  there  is  a  notable 
development  of  steps  or  benches  due  to  the  stoping  action  in  cirque 


GLACIERS  OF  GLACIER  NATIONAL  PARK 


21 


formation  being  carried  on  at  several  different  levels.  These  arc  good 
examples  of  steps  in  a  so-called  “  glacial  staircase.”  There  are  two 


Fig.  8. — Grinnell  Glacier,  upper  part,  crest  of  moraine  in  foreground. 

Gem  Glacier  above  at  left. 

Photograph  by  T.  W.  Stanton. 


Fig.  9. — Moraine  of  Grinnell  Glacier. 

Piegan  Mountain  in  background. 

Photograph  by  T.  W.  Stanton. 

of  these  benches  in  the  upper  part  of  the  cirque,  and  on  these  lie  four 
distinct  little  glaciers  (fig.  11). 


22 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


Iceberg  Lake  and  Glacier. — The  charm  of  the  view  at  the  head  of  the 
North  Fork  of  Swiftcurrent  Creek  lies  in  the  combination  of  the  3,000- 
foot,  vertical,  encircling  wall  of  the  amphitheater,  the  small  glacier 
lying  at  its  base,  the  beautiful  little  lake  of  deepest  blue,  and  the  daz- 


Fig.  10. — Front  of  Gem  Glacier;  on  the  Garden  Wall 

ABOVE  GrINNELL  GLACIER. 

Photograph  by  T.  W.  Stanton. 

zling  whiteness  of  the  small  icebergs  usually  floating  in  the  lake  (fig. 
14).  With  these  masses  of  glacier  ice  there  are  usually  cakes  of  lake  ice 
floating  even  in  August.  Along  the  east  shore  of  the  lake  is  an  “ice 
rampart”  of  bowlders  probably  pushed  up  by  the  forward  crowding 
of  the  ice  when  the  lake  is  frozen  over  in  the  winter. 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


23 


Crossing  the  shallow  outlet  stream  one  finds  a  way  along  the  talus 
slope  and  over  the  ledge  around  the  north  shore  of  the  lake.  There 
is  a  considerable  accumulation  of  angular  and  unworn  rock  fragments 
piled  on  the  ice  at  the  north  side.  This  has  evidently  fallen  from  the 
cliffs  and  has  been  handled  by  the  glacier  only  enough  to  pile  up  sharp 
morainal  ridges  30  to  40  feet  in  height.  Crossing  these  one  reaches 


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the  main  part  of  the  glacier  (fig.  15),  upon  which  there  is  also  a  sprink¬ 
ling  of  rock  fragments.  Toward  the  front  the  ice  is  broken  by 
crevasses  (fig.  16),  and  much  of  this  drift  must  fall  into  these  yawning 
cracks,  and  thus  reach  the  base  of  the  ice,  there  to  be  ground  and 
polished  beneath  the  moving  glacier  and  pushed  forward  into  the  lake. 
In  the  ice  walls  of  these  crevasses  the  banded,  stratified  structure  of 
the  ice  is  well  displayed.  In  that  part  south  of  the  morainal  ridge 
where  seen  by  the  writer,  the  banding  is  longitudinal,  i.  e.,  parallel  to 


Fig.  12. — Sperry  Glacier  from  Little  Ma' 

Fhotograp 


Fig.  13. — Blackfeet  Glacier,  eastern  part,  Black] 

Photograph 


RHORN,  GUNSIGHT  MOUNTAIN  IN  BACKGROUND. 


W.  C.  Alden. 


t  Mountain  and  Jackson  Mountain  in  background. 

W.  C.  Alden. 


26 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


the  direction  of  the  ice  flow,  and  it  is  seen  in  the  sides  of  the  crevasses 
to  dip  southward  at  an  angle  of  from  30°  to  45°.  In  the  front 
of  the  glacier  this  dip  is  seen  to  decrease  southward  and  become  nearly 
horizontal  or  slightly  undulating  and  to  extend  thus  across  the  glacier. 


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Toward  the  south  side  the  banding  appears  to  curve  again  downward 
at  a  high  angle  which  decreases  again  townrd  the  south  wall. 

The  front  of  the  glacier  is  now  nearly  a  mile  back  from  the  crest  of 
the  cliff  over  wdrich  the  trail  climbs  to  the  upper  cirque.  Striations 
on  the  rock  ledges  east  of  the  lake  show  that  at  some  former  time  the 
ice  extended  across  and  beyond  the  rock  basin  in  wdiich  the  lake  now 
lies.  Loosened  and  partially  removed  blocks  of  rock  at  and  near  the 
cliff  between  the  lower  valley  and  the  upper  cirque  suggest  the  method 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


27 


Fig.  15. — Front  op  glacier  at  Iceberg  Lake. 
Photograph  by  W.  C.  Alden. 


Fig,  16, — Glacier  at  Iceberg  Lake  showing  crevasses  and  rock  debris  on 

the  ICE. 


Photograph  by  W.C.  Alden. 


28 


GLACIERS  OF  GLACIER  NATIONAL  PARK 


DUE  TO  GLACIATION. 
J’holograph  by  M.  R.  Campbell. 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


29 


by  which  the  more  extended  moving  ice  was  stoping  back  the  cliff 
face  when  the  melting  of  the  ice  ended  the  operation. 

Canyon  Creek  Glacier. — Above  the  beautiful  lake  at  the  head  of  Can¬ 
yon  Creek  one  may  cross  the  alluvial  fan  and  climb  the  steep  slope  of  the 
moraine  which  is  being  built  up  by  a  small  glacier.  The  glacier,  which 
is  almost  covered  with  rock  fragments  fallen  from  the  great  encircling 
cirque  wall,  is  considerably  crevassed  as  though  crowding  forward  over 
the  lip  of  the  cirque.  A  still  higher  bench  in  the  back  of  the  cirque 
holds  a  small  crevassed  glacier  and  high  up  upon  the  west  side  in  a 
niche  above  a  projecting  ledge  is  a  third. 

Former  extent  of  the  ice. — The  broadly  rounded,  U-shaped  profiles  of 
the  valley  (fig.  17),  the  oversteepened  side  slopes  with  small  amount 
of  talus,  the  glaciated  rock  ledges,  and  deposits  of  glacial  drift,  to¬ 
gether  with  other  general  relations,  indicate  that  during  the  last,  or 
Wisconsin,  stage  of  the  glacial  period,  Swiftcurrent  Valley  and  all  its 
tributaries  were  occupied  by  a  great  glacier  which  was  in  turn  tribu¬ 
tary  to  a  former  glacier  which  may  be  called  the  St.  Mary  glacier  (see 
map  facing  page  32).  The  small  existing  glaciers  described  above  are 
the  diminutive  remnants  of  this  great  stream  of  ice.  The  height  to 
which  Swiftcurrent  Valley  was  filled  by  this  glacier  is  not  definitely 
known,  but  it  probably  reached  2,000  or  2,500  feet.  High  upon  the 
mountain  slope  to  the  north,  about  1,600  feet  above  the  outlet  of 
McDermott  Lake,  the  writer  observed  rock  ledges  which  had  been 
polished  and  striated  by  ice  moving  eastward  down  the  valley.  Simi¬ 
lar  striae  were  also  seen  on  the  northwest  slope  of  Allen  Mountain  at 
about  the  same  height  above  the  lake.  About  5  miles  farther  east 
where  this  glacier  joined  the  trunk  of  the  former  St.  Mary  glacier  the 
ice  must  have  been  at  least  1,000  feet  thick,  judging  from  the  eleva¬ 
tions  of  the  moraine  which  incloses  Duck  Lake,  3  to  6  miles  east  of  the 
village  of  Babb. 

BELLY  RIVER  GLACIERS. 

Glaciers  at  Ahern  Pass. — From  Granite  Park  a  trail  leads  northward 
to  Ahern  Pass.  By  this  route  one  may  cross  the  divide  and  descend 
Belly  River  Valley.  From  the  pass  down  to  the  upper  lake  the  trail 
is  passable  for  pedestrians  using  caution  but  is  not  in  condition  for 
saddle  or  pack  animals.  August  22,  1890,  Lieut.  George  P.  Ahern  1 
led  a  party,  consisting  of  a  detachment  of  soldiers  from  the  Twenty- 
fifth  Infantry,  Mr.  G.  E.  Culver  and  two  prospectors,  with  packers, 
Indian  guides,  and  a  pack  train,  up  Belly  River  Valley  and  across  the 
pass  which  bears  his  name. 

One  interesting  feature  of  this  trail  is  that  after  passing  the  divide 
it  leads  down  across  the  upper  part  of  the  sloping  surface  of  a  small 
glacier  and  then  passes  out  along  the  steep  valley  side,  which  is  cov- 

1  Notes  on  a  little  known  region  in  northwestern  Montana,  by  G.  E.  Culver,  Trans.  Wis.  Acad.  Sci., 
vol.  8,  pp.  185-205,  1888-91. 


30 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


ered  with  loose  sliding  rock  excepting  where  there  are  precipitous 
rock  ledges.  The  surface  of  the  small  glacier  descends  steeply  about 
500  feet  to  the  crest  of  a  cliff  which  drops  down  thence  1,000  feet  to 
the  head  of  the  valley  below  (fig.  IS).  The  angle  of  slope  of  the  ice 
for  several  hundred  feet  above  its  foot  is  about  45°,  and  this  steep 
slope  is  in  part  scored  by  open  crevasses.  It  is  not  a  suitable  place 
for  coasting.  This  glacier  occupies  a  niche  in  the  upper  south  wall  of 
the  great  cirque  just  below  the  pass.  The  main  head  wall  of  the 
amphitheater  is  one  of  the  most  imposing  in  the  park.  The  peak  at 
its  crest  north  of  the  pass  stands  nearly  3,600  feet  above  the  upper 
lake.  Of  this  the  upper  2,500  feet  stands  almost  vertical.  Below 
this  some  small  glaciers,  with  their  neve  banked  against  the  base  of 
the  cliff,  spread  out  slightly  on  the  rock  bench  above  the  lake.  These 


Fig.  18. — Glacier  at  Ahern  Pass. 

Photograph  by  T.  W.  Stanton. 

are  bordered  by  comparatively  large  moraines.  One  of  these  as  seen 
from  above  surrounds  the  narrow  end  of  the  glaciers  as  a  sharp  V, 
like  the  nose  of  a  snow  plow  (fig.  19.)  The  ice  appears  to  be  thinned 
as  the  ridge  stands  up  abruptly  from  its  debris-covered  surface.  A 
short  distance  outside  this  is  an  earlier  moraine  covered  with  vegeta¬ 
tion  and  encircling  a  pond  of  water. 

At  the  top  of  the  vertical  northwest  wall  of  the  cirque  is  another 
glacier  about  2,600  feet  above  the  lake.  This  lies  500  feet  or  more 
above  the  level  of  Ahern  Pass  so  that  only  its  front  edge  can  be  seen 
from  that  point.  To  one  looking  down  upon  it  from  the  mountain 
top  above  it  appears  as  a  considerable  mass  of  ice  with  a  width  from 
north  to  south  of  seven-tenths  of  a  mile  and  a  length  from  northwest 
to  southeast  of  one-half  mile.  The  frontal  margin  is  pushed  forward 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


31 


quite  to  the  crest  of  the  cliff  and  in  places  appears  to  overhang  so 
that  the  drift  as  it  is  thrust  forward,  and  doubtless  some  of  the  ice 
also,  falls  over  the  precipice  and  the  streams  hang  on  the  dark  rock 
wall  like  silvery  threads. 

Chaney  Glacier. — From  a  camp  on  Flattop  comparatively  easy 
access  to  the  glaciers  at  the  head  of  Middle  Fork  of  Belly  River  is 


Fig.  19. — Glaciers  and  moraines  near  Ahern  Pass. 

Photograph  by  W.  C.  Alden. 

gained  by  climbing  to  the  potch  in  the  crest  of  the  mountain  wall  at 
the  head  of  Mineral  Creek.  All  five  of  these  glaciers  occupy  scallops 
in  the  great  upper  cirque,  above  the  tops  of  the  cliffs  against  which 
head  the  main  floors  of  the  two  branches  of  the  Middle  Fork. 

From  the  notch,  which  is  at  about  7,950  feet  above  sea  level,  one 
sees  Chaney  Glacier  spread  out  at  his  feet.  This  glacier  was  named 


32 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


in  honor  of  Prof.  L.  W.  Chaney,  jr.,1  of  Carleton  College,  of  North- 
field,  Minn.,  who  visited  it  in  1895. 

Chaney  Glacier  (fig.  20)  has  a  width  from  northwest  to  southeast 
of  about  1  mile.  From  its  upper  edge,  about  15  or  20  feet  below  the 


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notch  in  the  divide,  the  smooth  surface  of  the  ice  slopes  northward. 
At  the  top  the  slope  is  gentle,  but  toward  the  front  it  is  steeper, 
descending  about  1,200  feet  in  a  distance  of  one-half  mile.  At  the 
north  side  of  the  eastern  part  of  the  glacier  the  ice  extends  as  a  nar¬ 
rowing  tongue  down  into  a  notch  in  the  lip  of  the  upper  cirque. 


1  Appalachia,  Vol.  VIII,  1896-1898. 


ALBERTA 

MONTANA 


C  lit  b  (vh 


‘owinnnmi 


'  V  .  .  \  if  ■  <V  I 

Jpl*  y  '  1 H  1 1 : 

.jfof  EASTERN  PORTION  OF 

V*  GLACIER  NATIONAL  PARK 

j  AND  ITS  ENVIRONS 

DURING  THE  GREAT  ICE  AGE 


iffflaciprlPstrk'' 


PSiummimt 


Extent  of  Rocky  Mountain  glaciers  and  Keewatin  ice  sheet 
during  the  last  or  Wisconsin  stage  of  glaciation. 

Areas  in  which  deposits  of  the  earlier  or  pre-Wisconsin 
mountain  glaciers  and  associated  gravel  are  preserved  on 
remnants  of  the  older  high-level  plains. 

Mountain  crests  and  rock  surfaces  that  were  probably  not 
covered  by  the  Rocky  Mountain  glaciers. 


.lijHeart  Butte 


Areas  in  which  glaciers  exist  at  present 

Wm.  C.  Alden  and  Eugene  Stebinger,  U.  S.  Geological  Survey.  1914. 


0 


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20  MILES 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


33 


The  smooth  surface  of  the  glacier  is  banded  from  side  to  side  by 
curving  zones  of  darker  color.  These  are  the  soiled  zones  due  to  the 
concentration  of  dust  and  small  rock  fragments  which  accumulated 
on  the  surface  of  each  successive  winter’s  snowfall.  They  thus  dif¬ 
ferentiate  the  outcropping  edges  of  the  ice  strata  of  which  the  glacier 
is  composed. 

When  seen  by  the  writer  in  1911  and  1913  the  ice  was  but  very  little 
crevassed,  though  a  few  cracks  were  open  near  the  front  of  the  lobe 
and  in  the  upper  part  the  latter  were  partially  filled  with  snow. 
Interesting  features  seen  in  a  few  places  were  ice  dikes  6  or  8  inches 
thick.  These  are  formed  by  water  freezing  in  the  cracks.  When 
subsequently  there  has  been  a  little  melting  at  the  surface  the  parallel 
crystals  may  be  raked  out  loosely  with  a  pick.  Similar  but  radial 
structures  are  seen  in  several  places  where  circular  cavities  several 
inches  in  diameter  have  been  filled  by  ice  crystals  growing  converg- 
ently  from  the  encircling  ice  wall  toward  the  center  of  the  cavity. 
Such  features  were  called  “gletschersternen,”  or  “glacier  stars,”  by 
Prof.  Agassiz. 

About  250  yards  below  the  notch  in  the  divide  by  which  the 
glacier  is  reached  from  the  south  there  is  a  zone  extending  laterally 
part  way  across  the  glacier  in  which  there  are  many  ice  wells  or 
moulins.  These  are  vertical  holes  hi  the  ice  varying  in  diameter 
from  1  to  6  feet.  Many  of  them,  especially  those  into  which  stream¬ 
lets  of  water  plunge  after  flowing  on  the  surface  of  the  ice,  appear 
to  extend  to  the  bottom  of  the  glacier.  Others  from  which  the 
streams  have  been  diverted  are  partially  filled  with  snow.  Sound¬ 
ings  made  by  the  writer  in  several  of  the  wells  with  a  cord  and  stone 
show  depths  ranging  from  25  to  74  feet,  the  deepest  being  near  the 
center  of  the  main  ice  stream.  These  are  regarded  as  measures  of 
the  thickness  of  the  ice  at  these  several  points,  since  it  seems  prob¬ 
able  that  the  water  descends  to  the  rock  floor  of  the  cirque  before 
flowing  away  beneath  the  ice.  These  wells  are  arranged  in  lines 
transverse  to  the  direction  of  ice  flow  and  appear  to  have  been 
developed  along  cracks  which  now  at  least  are  tightly  closed  though 
visible.  At  points  where  cracks  were  opened  across  the  course  of 
rivulets,  or  where  rivulets  developed  across  cracks  already  opened, 
percolation  of  water  down  the  cracks  may  have  initiated  the  thaw¬ 
ing  of  holes  which  were  gradually  enlarged  to  their  present  dimen¬ 
sions.  These  wells  were  not  noted  farther  down  the  slope  in  the 
central  part  of  the  glacier.  It  may  be  that  along  this  zone  is  a  posi¬ 
tion  where  successive  cracks  develop,  though  there  are  no  open 
crevasses  at  this  place.  After  one  set  of  cracks  and  moulins  have 
developed  and  moved  a  short  distance  down  the  slope  the  opening 
of  new  cracks  in  the  former  position  may  lead  to  the  development 


34 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


of  a  new  set  of  moulins,  giving  new  apertures  by  which  the  wTater  is 
diverted  to  the  base  of  the  ice  above  the  former  line  of  wells.  Sub¬ 
sequently  these  latter  may  become  filled  with  snow  and  contracted 
by  pressure  until  no  openings  remain.  In  a  direction  somewhat 
west  of  north  from  the  notch  in  the  divide,  at  the  'west  side  of  the 
main  current  to  the  frontal  lobe  of  the  glacier  is  a  mound  of  buff 
argillite  fragments.  About  the  head  or  south  side  of  this  are  clus¬ 
tered  many  of  these  ice  wells,  so  that  this  part  of  the  glacier  must  be 
crossed  with  care. 

Near  the  w7est  side  of  this  mound  was  seen  a  larger  hole  about  15 
feet  long  shaped  like  a  bathtub.  This  w’as  filled  with  water  to 
within  a  few  feet  of  the  surface  and  in  the  w’ater  floated  a  tiny  ice¬ 
berg.  This  is  a  good  example  of  the  cavities  designated  “  baignoires,” 
or  “bathtubs,”  by  Prof.  Agassiz.1  Soundings  showed  this  “bath¬ 
tub”  to  be  12  feet  deep.  It  is  not  evident  what  would  cause  the 
development  of  so  deep  a  cavity  in  the  ice,  as  it  appears  not  to  be 
due  to  running  water,  at  least  the  bottom  and  sides  are  now  so 
tightly  closed  that  the  water  is  retained.  Possibly  it  was  once  a 
moulin  like  those  farther  up  the  slope,  which  after  being  abandoned 
by  the  stream  of  wTater  became  partly  filled  with  snow  and  tightly 
closed  by  refreezing.  Prof.  Agassiz  describes  baignoires  in  which 
there  is  no  debris  as  probably  due  to  the  closing  up  of  crevasses. 

“Dust  wells”  are  seen  frequently.  They  are  small  vertical 
holes  in  the  surface  of  the  ice,  a  few’  inches  in  diameter,  and  a  few’ 
inches  deep  with  a  little  dirt  at  the  bottom.  At  points  w’here  a 
small  thin  patch  of  dirt  lies  on  the  ice  this  dirt  absorbs  more  heat 
from  the  sun  than  the  surrounding  ice  and  causes  more  rapid  melting. 
Settling  of  the  dirt  with  the  melting  of  the  ice  deepens  the  hole  until 
it  reaches  the  limit  of  depth  to  which  the  sun’s  rays  can  penetrate 
the  cavity. 

The  opposite,  or  protective,  effect  of  rock  debris  upon  the  surface 
of  the  ice  is  w  ell  illustrated  by  the  mound  of  rock  fragments  referred 
to  above.  This  mound,  which  is  15  or  20  feet  high,  is  probably 
principally  of  ice,  but  is  completely  covered  by  the  rock  fragments. 
Prof.  Chaney  2  mentions  such  a  “surface  moraine  of  yellow  slate,” 
evidently  the  same  rock-covered  ice  mound,  as  having  been  seen  by 
him  in  1895.  Apparently  many  years  ago  a  mass  of  rock  fell  onto 
the  ice  from  the  cliff  at  the  back  of  the  glacier  and  with  the  advance 
of  the  ice  this  has  gradually  moved  forward.  Meanwhile  the  sur¬ 
rounding  ice  surface  has  been  lowered  by  melting  while  the  ice 
beneath  the  rock  pile  has  been  protected  from  melting.  As  the 
surrounding  ice  disappeared,  rock  fragments  slid  down  the  sides  of 
the  mound  so  as  to  cover  the  ice  core.  From  this  mound  a  belt  of 
scattered  drift  extends  forward  like  a  medial  moraine  to  the  front 
of  the  glacier. 


1  System  Glaciare,  1847,  p.  100. 


2  Op.  cit.,  p.  796. 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


35 


Excepting  at  the  point  of  the  lobe,  the  glacier  is  bordered  by  a 
strongly  marked  marginal  moraine  20  to  30  feet  in  height.  At  the 
extremity  of  the  ice  tongue  the  drift  has  been  pushed  over  the  cliff, 
though  at  present  the  ice  is  a  short  distance  from  the  crest.  One 
part  of  this  moraine  is  largely  composed  of  large  and  small  fragments 
of  lava  ( amygdaloidal  trap  rock).  At  a  place  west  of  the  notch  in 
the  divide  a  bed  of  this  rock  extends  to  the  top  of  the  divide  and 
there  yields  fragments  which  fall  onto  the  ice.  Such  lava  blocks 
are  scattered  all  the  way  across  the  glacier  from  the  place  where 
these  blocks  fall  to  the  morame. 

September  6,  1913,  the  writer  attempted  some  crude  measure¬ 
ments  on  the  rate  of  movement  hi  the  glacier.  On  the  west  margin 
of  the  frontal  lobe  at  a  point  about  opposite  the  curve  in  the  moraine 
a  spike  was  set  at  10.35  a.  m.  hi  the  ice  45  inches  in  advance  of  a 
mark  placed  on  the  rock  ledge.  At  4.15  p.  m.  the  distance,  as 
nearly  as  could  be  determined,  the  spike  having  been  slightly  dis¬ 
placed  by  melting,  had  increased  to  45J  inches,  an  advance  of  one- 
eighth  inch  in  5  hours  and  40  minutes.  This  was  at  the  side  of  the 
lobe  where  it  would  seem  that  the  movement  would  be  much  less 
rapid  than  in  the  center  of  the  stream. 

At  a  point  near  the  extremity  of  the  narrowed  lobe  a  spike  was  set 
at  10.50  a.  m.  in  the  ice  37|  inches  in  the  rear  of  a  mark  on  the  rock 
ledge.  At  4.03  p.  m.  this  distance  had  decreased  to  37^  inches, 
indicating  an  advance  of  one-eighth  inch  in  5  hours  and  13  minutes. 

Sue  Lake  and  Glacier. — Going  westward  from  Chaney  Glacier  past 
the  spur  of  the  mountain  one  finds  a  beautiful  little  lake  of  blue  lying 
in  a  rock  basin  in  the  next  scallop  of  the  great  cirque.  At  the  head  of 
the  lake  is  a  tiny  glacier  lying  at  the  foot  of  the  great  cirque  wall.  A 
strongly  marked  moraine  30  to  40  feet  high  borders  the  front  of  the 
ice  at  the  edge  of  the  lake,  excepting  for  an  interval  where  a  narrow 
tongue  of  the  ice  projects  through  and  into  the  lake.  From  this 
ice  small  bergs  break  off  and  float  in  the  lake.  A  narrow  cliff  glacier 
lies  on  a  bench  in  the  south  wall  high  above  the  lake.  The  outlet 
stream  from  the  lake  flows  a  few  rods  over  rock  ledges  and  then 
plunges  300  to  400  feet  down  the  cliff  to  a  lower  compartment  of  the 
great  cirque. 

Shepard  Glacier. — Crossing  the  creek  which  flows  from  Sue  Lake 
and  climbing  over  the  ledges  west  of  the  outlet  one  reaches  Shepard 
Glacier  (fig.  21).  This  glacier  was  named  for  E.  11.  Shepard,  of 
Minneapolis,  who  visited  this  region  in  company  with  Prof.  L.  W. 
Chaney  in  1895  and  subsequently. 

This  small  glacier  has  an  extent  from  northwest  to  southeast  of 
about  one-half  mile  and  from  southwest  to  northeast  of  about  three- 
tenths  of  a  mile.  It  occupies  two  levels  of  the  cirque,  the  northern 
part  being  divided  by  a  rock  cliff.  The  main  part  cascades  over 


36 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


this  cliff  and  in  so  doing  is  broken  by  great  yawning  crevasses  which 
are  closed  again  in  the  steeper  slope  below. 

The  front  of  each  of  the  northern  arms  of  the  glacier  is  bordered  by 
a  morainal  embankment,  for  which  there  is  barely  room  at  the  tops 
of  the  cliffs.  At  the  south  side  of  the  main  glacier  is  a  moraine  piled 
5  to  25  feet  high.  In  places  the  ice  margin  is  melted  back  50  to  70 
feet  from  this  moraine.  The  dirt  bands  marking  the  edges  of  the  ice 
strata  show  plainly.  From  the  lower  ice  front  a  stream  of  water 
plunges  several  hundred  feet  down  the  cliff  to  the  lower  cirque  floor. 

Glacier  southeast  of  Clianey  Glacier. — Across  the  mountain  wall  on 
the  southeast  side  of  Chaney  Glacier  is  another  small  glacier  poking 
its  nose  into  a  little  lake,  which  lies  in  a  rock  basin  behind  the  lip  of 


Fig.  21. — Shepard  Glacier. 

Photograph  by  W.  C.  Alden. 

the  upper  cirque.  When  seen  by  the  writer  from  the  top  of  the 
cirque  wall  in  August,  1911,  this  lakelet  was  dotted  with  floating 
masses  of  ice  which  had  broken  off  from  the  glacier  front.  The 
water  which  overflows  the  lip  of  the  cirque  plunges  1,500  feet  to  a 
second  lake  in  the  head  of  the  valley. 

Former  extent  of  the  ice  in  Belly  River  Valley. — There  are  several 
other  small  glaciers  in  the  heads  of  tributaries  to  the  Middle  and 
North  Forks  of  Belly  River  Valley,  last  remnants  of  the  great  Belly 
River  Glacier. 

From  an  examination  of  the  valley  and  of  the  deposits  therein 
north  of  the  international  boundary  it  is  known  that  at  the  last  stage 
of  the  Glacial  Period  Belly  River  Valley  was  occupied  by  a  great 
glacier  extending  from  the  Continental  Divide  northeastward  across 
the  international  boundary  into  southern  Alberta,  a  distance  of  at 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


37 


least  30  miles  (see  map  facing  p.  32).  No  detailed  study  of  the 
glacial  phenomena  has  yet  been  made  throughout  this  valley  and  its 
several  tributaries,  but  there  is  reason  for  thinking  that  at  a  point  3 
miles  south  of  the  forty-ninth  parallel,  or  10  miles  from  the  Conti¬ 
nental  Divide,  the  ice  in  the  valley  was  at  least  800  feet  thick. 

GLACIERS  IN  THE  NORTHWESTERN  PART  OF  THE  PARK. 

Vulture  Peak  Glaciers. — An  interesting  area  of  glaciers  and  glacial 
phenomena  is  accessible  either  from  a  camp  site  in  the  upper 
part  of  Little  Kootenai  Creek  Valley  or  from  one  at  the  head  of  the 
South  Fork  of  Valentine  Creek.  From  either  site  one  can  reach  the 
top  of  the  ridge  between  these  two  valleys  by  trail  and  go  thence 
west  over  the  divide.  A  somewhat  more  difficult  and  precarious 
climb  may  be  made  up  along  the  face  of  the  cliffs  on  either  the  north 
or  the  south  side  of  the  lake  at  the  head  of  Little  Kootenai  Creek  to 
the  notch  in  the  divide,  from  which  the  glaciers  on  the  east  slope  of 
Vulture  Peak  are  easily  reached.  The  latter  courses,  however,  are 
hot  to  be  recommended  to  inexperienced  tourists.  Between  Vulture 
Peak  and  the  ridge  on  the  east  is  a  considerable  bench  or  rock  floor 
whose  relations  suggest  that  it  is  part  of  the  floor  of  an  old  cirque 
developed  by  a  glacier  in  the  Quartz  Creek  Valley  from  which  the 
south  wall  was  cut  away  by  the  headward  stoping  of  glaciers  which 
occupied  Little  Kootenai  and  Logging  Creek  Valleys.  Three  small 
lakelets  occupy  basins  in  this  rock  floor,  and  on  the  mountain  slope 
to  the  west  are  the  glaciers.  The  upper  and  larger  one  occupies  two 
or  more  levels.  The  upper  part  has  a  steep  surface  and  is  much 
crevassed,  and  it  extends  down  to  the  crest  of  a  cliff  and  pushes  its 
drift  over  to  fall  to  the  bench  below.  Farther  south  a  narrow  and 
much  crevassed  portion  of  the  ice  extends  down  over  the  cliff  to  that 
part  of  the  glacier  which  spreads  out  on  the  bench  around  to  the 
east.  This  part  extends  to  the  crest  of  a  lower  cliff  or  ledge  and 
thrusts  its  load  of  drift  over  to  fall  below.  The  surface,  especially 
near  the  front,  is  much  broken  by  transverse  and  longitudinal  crev¬ 
asses.  A  morainal  embankment  extends  from  the  foot  of  the  ledge 
to  the  northwest  side  of  the  upper  lakelet,  showing  that  the  ice  has 
been  more  extensive.  Below  the  south  end  of  the  ledge  a  separate 
tiny  glacier  extends  down  to  the  water  in  the  upper  little  lake.  The 
drainage  from  these  glaciers  is  tributary  to  Quartz  Creek. 

On  the  ledges  just  east  of  this  body  of  ice  there  is  a  fine  display  of 
the  results  of  glacial  abrasion  in  the  form  of  smoothing,  polishing, 
striating,  and  grooving  (fig.  22) .  This  is  to  be  seen  both  on  northcast¬ 
dipping  rock  surfaces  and  on  vertical  joint  faces.  Upward -curving 
striae  show  where  the  ice  rode  up  over  ledges  which  projected  in  its 
path. 

Farther  south  at  the  foot  of  the  northeast  slope  of  the  mountain 
spur  lies  another  small  glacier.  This  is  unique  in  that  the  water 


38 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


from  the  northern  part  escapes  across  the  upturned  rock  ledges  and 
finds  its  way  to  and  over  the  cliff  at  the  head  of  Little  Kootenai 
Valley,  thus  being  tributary  to  Hudson  Bay.  The  water  from  the 
southern  part  of  the  glacier  flows  southeastward  along  the  strike 
behind  a  rock  ridge  and  finally  plunges  down  the  cliffs  at  the  head 
of  Logging  Creek  Valley  and  becomes  tributary  to  Columbia  River 
and  the  Pacific  Ocean.  Because  of  this  relation  the  proposal  has 
been  made  to  call  this  Two  Ocean  Glacier.  Striae  on  the  ledges  in 
front  of  this  glacier  show  that  it  was  formerly  larger,  and  extended 
southeastward  to  the  saddle  between  the  heads  of  Little  Kootenai 


Fig.  22. — Glacial  grooves,  Vulture  Peak. 

Photograph  by  M.  R.  Campbell. 

and  Logging  Creeks.  The  southerly  trend  of  striae  in  this  saddle 

Oo  O  J 

indicates  that  the  ice  joined  a  great  Logging  Creek  glacier. 

From  the  crest  of  the  southeast  spur  of  Vulture  Peak  there  is  a  fine 
view  of  Vulture  Glacier,  which  lies  in  an  upper  cirque  in  the  south 
side  of  the  mountain  mass  more  than  3,000  feet  above  the  lakes  in 
the  head  of  Logging  Creek  Valley.  From  the  notch  in  this  creek  one 
can  easily  reach  this  glacier.  The  glacier  and  neve  have  a  width 
from  southwest  to  northeast  of  about  four-fifths  of  a  mile  and  a  length 
from  northwest  to  southeast  of  about  seven-eighths  of  a  mile.  From 
the  neve  at  the  back  the  ice  descends  with  a  slope  of  15°  to  20°,  which 
increases  rapidly  toward  the  front  where  several  lobes  cascade  down 
over  the  ledges  into  notches  in  the  lip  of  the  upper  cirque.  The  total 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


39 


descent  from  the  gaping  bergschrund  near  the  top  of  the  neve  slope 
to  the  end  of  the  lowest  lobe  is  1,000  feet  or  more.  The  surface  of 
the  ice  is  smooth  and  banded  from  side  to  side  with  soiled  zones 
marking  the  outcropping  of  the  glacial  strata. 

That  part  of  the  glacier  south  of  the  end  of  the  bifurcating  ledge 
is  so  broken  by  crevasses  as  not  to  be  readily  crossed. 

In  places  there  are  morainal  deposits  some  distance  below  the  ends 
of  the  frontal  lobes.  One  of  the  small  lobes  has  been  considerably 
larger,  as  shown  by  the  fact  that  there  is  a  lateral  moraine  lying  on 
a  bench  50  or  60  feet  higher  and  several  rods  farther  south  than  the 
edge  of  the  ice.  The  front  slope  of  this  lobe  is  about  27°. 

On  August  27,  1913,  several  attempts  were  made  to  measure  the 
rate  of  ice  movement.  Not  far  from  the  end  of  the  main  lobe  a  spike 
was  set  in  the  ice  at  2.30  p.  m.,  26 J  inches  in  advance  of  a  mark  on 
the  underlying  rock.  At  3.30  p.  m.  the  distance  had  increased  to 
26f  inches,  an  advance  of  one-half  inch  in  one  hour.  Markers  set  at 
the  northeast  side  of  the  same  lobe  several  hundred  feet  higher  up 
showed  no  advance  between  2.20  and  3.35  p.  m.  of  the  same  day, 
thus  indicating  retardation  of  movement  at  the  side  of  the  lobe. 
Markers  set  at  each  side  of  the  ledge  which  projects  through  the  ice 
showed  no  appreciable  advance  between  1  and  2  p.  m.  of  the  same 
day.  Evidently  the  flow  lags  about  this  ledge  just  as  the  recurved 
dirt  bands  seem  to  indicate.  Near  the  southeast  end  of  the  ledge 
which  bifurcates  the  glacier,  markers  were  set  at  1.30  p.  m.  on  this 
day,  and  when  reexamined  at  2  p.  m.  the  ice  had  moved  one-lialf 
inch. 

Carter  Glaciers. — On  the  upper  slope  at  the  head  of  Valentine  Creek 
near  Jefferson  Pass  are  two  small  glaciers  designated  the  Carter 
Glaciers,  in  honor  of  the  late  Senator  Carter  of  Montana.  The  most 
southerly  one  is  about  one-fourth  mile  in  extent  from  back  to  front 
and  about  three-fourths  of  a  mile  wide  from  northwest  to  south¬ 
east.  The  surface  is  smooth  and  shows  but  few  crevasses.  Though 
so  small  a  glacier,  the  front  is  bordered  by  a  morainal  embankment 
rising  in  places  50  feet  above  the  ice  on  the  inside  and  100  feet 
above  the  rock  on  the  outside.  The  ice  front  has,  in  part,  been  melted 
back  200  feet  from  the  summit  of  the  ridge,  but  elsewhere  it  is  pressed 
snugly  against  the  moraine. 

A  short  distance  farther  north  there  is  a  somewhat  larger  compound 
glacier  consisting  of  a  lower  main  body,  much  crevassed  because  of 
the  steepness  and  irregularity  of  slope,  and  two  distinct  smaller  ones 
higher  up  on  the  cliff.  The  upper  glacier  cascades  down  to  the  lower 
one.  Along  the  north  front  of  this  is  a  strong  moraine  with  reliefs 
of  60  to  70  feet  on  the  inside  and  80  to  100  feet  on  the  outside.  At 
the  center  of  the  front  the  ice  thrusts  its  load  of  drift  over  the  crest 
of  a  50-foot  cliff.  The  height  and  position  of  the  moraine  on  the  north 


40 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


side  indicate  that  at  some  time  the  glacier  has  had  considerably 
more  bulk  than  it  now  has. 

On  the  north  slope  of  Mount  Carter  is  a  small  glacier  more  resem¬ 
bling  the  valley  type  in  that  it  extends  through  the  contracted  open¬ 
ing  of  the  cirque  and  cascades  down  the  steep  slope  in  a  long,  narrow 


tongue.  The  ice  has  shrunken  away  from  its  strong  lateral  moraine. 
At  the  front  of  the  cascading  tongue  the  drift  is  dumped  down  the 
steep  slope.  It  is  this  glacier  which  furnishes  most  of  the  glacial 
silt  which  renders  so  milky  the  South  Branch  of  Bowman  Creek 
as  seen  from  the  trail  leading  to  Brown  Pass. 


Photograph  Gy  M.  U.  Campbell. 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


41 


Rainbow  Glacier. — From  the  mountain  ridge  east  and  north  of 
Vulture  Peak  there  is  a  fine  view  across  the  head  of  Quartz  Creek 
Valley  to  the  Rainbow  Glacier  nestling  in  an  upper  cirque  which 
scallops  the  mass  of  Cerulean  Eidge  on  the  east  flank  of  Rainbow 
Peak  (fig.  23). 

This  glacier  and  its  neve  has  a  breadth  from  northeast  to  southwest 
of  nearly  1  mile  and  a  length  from  northwest  to  southeast  of  1-J-  miles. 
The  entire  lower  half  is  much  crevassed  as  though  it  were  moving 
do  mi  over  a  steep  and  irregular  slope  broken  by  steps  or  ledges.  The 
maximum  descent  of  the  ice  is  about  2,000  feet.  At  about  the 
middle  of  the  front  of  the  glacier  a  tongue  about  100  yards  wide 
extends  by  cascading  down  to  a  ledge  about  200  feet  below  the  main 
front.  Excepting  in  the  south  part,  where  a  moraine  embankment 
borders  the  ice,  the  glacier  crowds  forward  to  the  very  verge  of  the 
cliff.  The  ice  in  places  seems  to  overhang  the  edge,  and  abrupt  ice 
cliffs  suggest  that  great  masses  of  ice  break  off  and  are  precipitated 
to  the  abyss  over  2,000  feet  below. 

Olson  Creek  glaciers. — Looking  southward  from  Brown  Pass  one 
sees  in  the  great  upper  cirque  a  glacier  which  has  a  width  of  nearly 
seven-eighths  of  a  mile  and  which  descends  about  1,200  feet  or  more 
in  the  three-fourths  mile  of  its  length.  This  may  be  reached  by  an 
easy  climb  of  a  few  hundred  feet  from  the  pass.  When  somewhat 
larger  than  it  was  when  seen  by  the  writer  in  August,  1913,  this  glacier 
pushed  its  terminal  moraine  near  the  crest  of  the  cliff  which  drops  to 
the  head  of  the  valley  below.  Since  that  time  the  ice  lias  shrunken 
somewdiat  from  the  moraine.  More  or  less  detached  portions  of  the 
glacier  lie  on  benches  in  the  cirque  wall  above  the  main  mass.  Rear 
the  front  the  ice  is  broken  by  crevasses,  some  of  which  are  10  to  15 
feet  wide  at  the  top  and  15  to  20  feet  deep.  In  the  walls  of  these 
crevasses  the  banding  of  the  ice  is  seen  to  dip  backward  upstream  at 
low  angle.  The  ice  exposed  here  carries  little  or  no  included  drift. 
At  one  point  where  the  foot  of  the  glacier  is  just  at  the  top  of  a  ledge 
the  ice  rides  free  a  foot  or  so  above  the  rock  for  a  distance  of  at  least 
25  to  30  feet  back  from  the  margin.  Looking  into  this  space  one  sees 
but  little  drift  in  the  bottom  of  the  ice.  Where  the  ice  is  grinding 
polishing,  and  scoring  the  rock  ledges  there  appear,  so  far  as  can  be 
seen,  to  be  but  a  thin  layer  of  fine  rock  flour  and  small  fragments 
between  the  clear  ice  and  the  rock  surface. 

These  and  other  small  glaciers  in  the  cirques  farther  east  are  the 
only  remnants  of  the  great  glacier  which  during  the  last  great  exten¬ 
sion  of  the  ice  occupied  Olson  Creek  Valley  and  was  tributary  to  the 
one  in  Little  Kootenai  Creek  Valley.  To  this  were  also  tributary 
the  glaciers  occupying  the  head  branches  of  this  valley  and  the  val¬ 
leys  of  Valentine  and  Boundary  Creeks.  It  is  known  that  at  the  last, 
or  Wisconsin,  stage  of  glaciation  this  great  trunk  glacier  extended 
northward  into  southern  Alberta.  Ten  or  twelve  miles  north  of  the 


42 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


boundary  line  the  deposits  of  this  glacier  pass  under  those  of  the  great 
continental  ice  sheet.  Observations  of  glacial  striae  high  upon  the 
mountain  slopes  at  the  head  of  Waterton  Lake  indicate  that  the  ice 
was  at  least  1,500  feet  thick  opposite  the  mouth  of  Olson  Creek  and 
it  was  probably  even  thicker  than  this. 

Boulder  Glacier. — Looking  westward  from  Brown  Pass  across  the 
great  cirque  at  the  head  of  Bowman  Creek  Valley,  one  sees,  high  up 
at  the  top  of  the  great  cirque  wall,  two  small  glaciers.  The  larger 
one  of  these  is  Boulder  Glacier  (fig.  24).  This  may  be  reached  from 
the  pass,  but  the  route  is  somewhat  hazardous  and  is  not  to  be  recom¬ 
mended  for  inexperienced  climbers.  The  bench  on  which  this  glacier 
rests  is  formed  by  a  lava  bed.  This  rock  emerges  from  beneath  the 


Fig.  24.— Boulder  Glacier,  Kintla  Peak  in  background. 

Thotograph  by  W.  C.  Alden. 


eastern  margin  of  the  ice  and  extends  thence  to  the  crest  of  the  wall 
of  the  lower  cirque.  In  this  interval  there  is  a  remarkable  exhibi¬ 
tion  of  the  effects  of  glaciation  produced  when  the  ice  had  a  some¬ 
what  greater  extent.  The  ledges  are  scored  with  striae  and  so 
smoothly  rounded  and  polished  as  to  offer  in  many  places  precarious 
footing  (fig.  25).  The  glacier  extends  westward  through  the  gap  in 
the  mountain  crest.  The  disposition  of  the  zones  marking  the  strati¬ 
fication  and  also  the  general  surface  slope  indicate  that  the  ice  now 
moves  toward  the  cliff  on  the  north  side  of  the  gap.  For  a  short  dis¬ 
tance  in  the  midst  of  the  gap  there  is  a  strong  morainal  embankment 
piled  25  to  35  feet  high  near  the  foot  of  the  mountain  ridge  on  the 
north.  This  moraine,  which  is  composed  of  intermingled  rock  flour 
and  partly  worn  and  partly  angular  rock  fragments  ranging  in  size 
from  a  fraction  of  an  inch  to  6-foot  blocks,  is  continuous  around  the 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


43 


west  side  of  the  mountain  ridge  and  also  about  the  western  part  of 
the  glacier. 

Emerging  from  beneath  the  western  part  of  the  glacier  the  lava 
bed  extends  westward  and  northward  as  the  floor  of  two  broad  gaps 
until  it  is  cut  off  at  the  crests  of  the  walls  of  two  lower  cirques  in 
which  head  branches  of  Kintla  Creek.  The  surface  of  this  uneven 
textured,  vesicular  rock  is  finely  glaciated,  exhibiting  strke,  gouges, 
and  beautifully  rounded  and  polished  roches  moutonnees. 

Boulder  Glacier,  together  with  four  tiny  glaciers  in  scallops  high 
up  in  the  walls  of  the  great  cirques  farther  southwest  and  the  cascad¬ 
ing  glacier  on  the  northeast  slope  of  Mount  Carter,  are  the  only  rem¬ 
nants  of  the  great  glacier  which  once  occupied  the  vaUey  of  Bowman 


Fig.  25. — Glaciated  lava  bed  in  front  of  Boulder  Glacier. 

Photograph  by  W.  C.  Alden. 

Creek  and  Lake.  On  the  north  slope  facing  the  lake,  opposite  Bain- 
how  Peak,  the  writer  observed  horizontal  glacial  stride  evidently  pro¬ 
duced  by  the  great  valley  glacier  1,100  feet  above  the  lake.  The  lake 
opposite  tliis  point  is  150  feet  deep,  so  that  it  is  known  that  the  great 
valley  glacier  must  have  had  a  thickness  of  at  least  1,200  or  1,300 
feet  opposite  Bainbow  Peak. 

AGASSIZ  AND  KINTLA  GLACIERS. 

From  the  mountain  slope  west  of  Boulder  Glacier  one  gets  a  dis¬ 
tant  view  of  Agassiz  Glacier,  one  of  the  finest  in  the  park,  on  the 
northeast  slope  of  Kintla  Peak  (fig.  26).  This  glacier  has  a  breadtli 
of  1.3  miles.  From  the  broad  main  part  of  the  mass  a  narrow 
tongue  extends  nearly  1 ,200  feet  lower  down  the  slope.  This  gives 
the  glacier  a  length  from  southwest  to  northeast  of  1.8  miles.  The 


44 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


ice  in  this  lower  tongue  is  much  crevassed.  West  of  this  lobe  a  mo- 
rainaj  embankment  borders  the  ice.  Agassiz  Glacier  has  a  vertical 
extent  of  about  2,000  feet,  the  lowest  point  being  about  5,800  feet 
above  sea  level.  The  glacier  is  said  to  be  accessible  from  Upper 
Kintla  Lake. 

On  the  opposite,  or  west,  side  of  Kintla  Peak  is  Kintla  Glacier 
(fig.  27),  having  a  breadth  of  more  than  2  miles,  but  an  area  about 
the  same  as  Agassiz  Glacier. 

EARLY  GLACIAL  HISTORY  OF  THE  REGION. 

Wisconsin  stage. — In  the  above  descriptions  of  the  glaciers  of  the 
park  reference  has  been  made  to  former  greater  extension  of  the  ice. 


Fig.  26. — Kintla  Peak  and  Agassiz  Glacier. 

Photograph  by  W.  C.  Alden. 

The  geological  studies  in  and  adjacent  to  the  park  have  developed 
evidence  that  there  were  at  least  two  and  possibly  three  different 
times  when  the  glaciers  extended  far  down  the  valleys  and  out  onto 
the  neighboring  plains.  These  extensions  of  the  mountain  glaciers 
were  probably  contemporaneous  with  the  development  and  deploy¬ 
ment  of  the  great  ice  sheets  which  covered  so  large  a  part  of  the 
North  American  Continent  during  the  several  stages  of  the  Glacial 
Period,  or  the  Great  Ice  Age.  As  is  the  case  in  the  study  of  the  phe¬ 
nomena  of  the  continental  ice  sheets,  so  also  the  study  of  Rocky 
Mountain  glaciation  has  developed  evidence  showing  that  the  epochs 
when  climatic  conditions  were  such  as  to  cause  great  extensions  of 
the  glaciers  alternated  with  epochs  when  conditions  were  similar  to 
those  of  the  present  so  that  the  glaciers  melted  away  and  the  valleys 
were  occupied  as  now  by  streams. 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


45 


On  the  map  facing  page  32  an  attempt  lias  been  made  to  repre¬ 
sent  graphically  conditions  as  they  were  in  the  mountains  and  on  the 
plains  east  of  the  park  during  the  maximum  of  the  last  great  stage, 
known  as  the  Wisconsin  stage,  of  glaciation.  On  this  map  the  moun¬ 
tain  valleys  are  shown  filled  with  ice  1,500  to  2,500  feet  thick,  the 


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glaciers  heading  in  the  many  cirques  and  extending  thence  down  the 
valleys  and  out  onto  the  plains.  The  crests  of  the  dividing  mountain 
ridges  are  represented  as  bare,  although  they  were  probably  hi  reality 
more  or  less  mantled  with  snow  and  ice.  The  map  shows  the  general 
relations  of  the  mountain  glaciers  to  the  border  of  the  great  Keewatin 
glacier  which  centered  on  the  Keewatin  plateau  west  of  Hudson 


46 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


Bay,  and  also  the  temporary  lake,  Cut  Bank  glacial  lake,  which  re¬ 
sulted  from  the  blocking  of  Cut  Bank  Creek  by  the  ice. 

Streams  of  ice  heading  in  the  mountain  valleys  now  drained  by 
Two  Medicine  and  Badger  Creeks  and  their  tributaries  coalesced  and 
spread  out  on  the  plain  as  a  great  piedmont  glacier,  known  to  geolo¬ 
gists  as  the  Two  Medicine  glacier.  This  glacier  had  a  maximum 
length  of  about  48  miles  and  a  breadth  of  30  miles.  The  knolled  and 
pitted  surface  of  its  morainal  deposits  may  be  seen  between  the  rail¬ 
way  and  the  flat-topped  ridge  5  miles  north  of  Glacier  Park  station. 
North  of  this,  ice  in  Lake  Creek  Valley  coalesced  with  a  glacier  in 
Cut  Bank  Valley.  Morainal  deposits  of  these  glaciers  are  crossed  by 
the  automobile  road  leading  from  Glacier  Park  station  to  St.  Mary 
Lakes. 

St.  Mary  Valley  was  occupied  by  a  great  trunk  glacier  which  so 
nearly  filled  the  valley  where  the  lakes  now  lie  that  it  deposited  a 
well-marked  lateral  moraine  at  the  top  of  the  ridge  on  the  east  1,200 
foot  or  more  above  the  lower  lake.  So  effectually  did  this  ridge  serve 
as  a  diverting  dam  that  the  greater  glacier,  instead  of  extending 
directly  eastward  onto  the  plains,  was  turned  northward  into  south¬ 
ern  Alberta.  Where  the  ridge  is  lower,  east  of  Babb,  the  ice  did 
extend  onto  the  upland,  and  a  lobe  deposited  a  strongly  marked 
moraine,  enclosing  the  basins  of  Duck  and  Goose  Lakes.  In  St. 
Mary  Valley  about  1  mile  south  of  the  boundary  the  drift  of  the 
St.  Mary  Glacier,  which  is  composed  entirely  of  material  from  the 
mountains,  is  overlapped  by  drift  of  the  continental,  or  Keewatin, 
glacier,  which  contains  granite  boulders  from  the  region  of  Hudson 
Bay.  Tributary  to  St.  Mary  Glacier  were  glaciers  in  the  valleys  of 
Kennedy,  Swiftcurrent,  Boulder,  Bed  Eagle,  and  Divide  Creek  Val¬ 
ievs. 

Drift  of  the  glaciers  which  at  the  same  time  occupied  Belly  Kiver 
and  Waterton  Lakes  valleys  is  also  overlapped  by  drift  of  the  conti¬ 
nental  glacier,  in  the  one  valley  about  9  miles  and  in  the  other  about 
12  miles  north  of  the  international  boundary. 

The  phenomena  in  the  western  part  of  the  park  indicate  that  the 
valleys  of  Kintla,  Bowman,  Quartz,  Anaconda,  Dutch,  and  Camas 
Creeks  and  those  farther  south  were  also  occupied  by  great  valley 
glaciers  during  the  Wisconsin  stage  of  glaciation.  The  actual  ex¬ 
tent  of  these  glaciers  has,  however,  not  yet  been  fully  determined. 
Terminal  moraines  have  been  found  in  Bowman,  Quartz,  and  Ana¬ 
conda  Creek  valleys,  but  it  has  not  been  determined  that  those  seen 
farthest  downstream  mark  the  limit  of  extension  of  the  glaciers  at 
the  Wisconsin  stage.  The  best  examples  of  these  deposits  are  the 
moraines  crossed  by  the  trail  below  Bowman  Lake  and  above  and 
below  Middle  Quartz  Lake. 

The  great  intramontane  basin  which  is  represented  by  West  Flat- 
top,  Flattop,  and  Granite  Park  and  similar  tracts,  and  into  the  bot- 


GLACIERS  OF  GLACIER  NATIONAL  PARK. 


47 


tom  of  which  are  cut  the  valleys  of  McDonald  and  Mineral  Creeks, 
is  believed  to  have  been  occupied  by  a  great  central  mass  of  ice 
which  discharged  principally  southwestward  by  the  McDonald 
Creek  Valley. 

To  this  stage  of  glaciation  was  probably  due  some  deepening  of 
the  previously-existing  stream-cut  valleys  and  the  broadening  and 
smoothing  of  sharp  V-shaped  cross  profiles,  produced  by  stream 
erosion,  to  the  wider  and  beautifully  rounded  U-shaped  profiles 
now  seen  (fig.  1,  A  and  B).  Also  most  of  the  excavation  of  the 
remarkable  cirques  which  scallop  the  slopes  of  the  great  mountain 
masses  was  accomplished  at  this  stage. 

Pre-  Wisconsin  glaciation . — The  Wisconsin  stage  of  glaciation  was 
preceded  by  a  long  period  during  which  the  glaciers  were  probably 
absent  or  much  reduced  in  size,  a  time  during  which  the  streams 
were  actively  engaged  in  sculpturing  the  great  mountain  mass,  in 
deepening  the  valleys,  and  in  eroding  and  washing  away  the  soft 
rocks  underlying  the  adjacent  plains. 

Prior  to  this  period  of  valley  cutting,  the  plains  bordering  the 
mountains  on  the  east  were  in  general  some  hundreds  of  feet  higher 
than  at  present  and  not  so  much  broken  by  hills  and  valleys.  In 
the  area  between  the  Great  Northern  Railway  and  the  international 
boundary  there  are  numerous  remnants  of  the  former  high  levels  of 
the  plains.  These  are  the  flat  tops  of  the  ridges  which  stand  between 
the  several  branches  of  Milk  River,  St.  Mary  River,  and  Cut  Bank 
Creek  (the  stippled  tracts  shown  on  the  map  facing  page  32).  Ex¬ 
amination  of  the  deposits  which  underlie  these  flat  tops  and  which 
overlie  the  upturned  and  beveled  edges  of  the  sandstones  and  shales 
forming  the  bulk  of  the  ridges  shows  that  a  large  part  at  least  are  of 
glacial  drift  derived  from  the  mountains.  The  relations  show  that 
long  ago,  before  the  valleys  which  now  separate  these  ridges  were 
eroded  and  when  the  various  remnants  yet  formed  a  continuous, 
nearly  flat  plain,  there  was  a  stage  of  glaciation  when  the  ice  heading 
in  St.  Mary  Valley  and  the  tributary  valleys  was  not  diverted  north¬ 
ward  by  St.  Mary  Ridge  and  the  great  trough  in  which  the  St.  Mary 
lakes  and  river  now  lie,  but  that  the  tributary  glaciers  united  in  a 
great  piedmont  glacier,  which  spread  directly  eastward  onto  the 
uneroded  plain.  Ice  from  Cut  Bank  and  Two  Medicine  Valleys 
probably  also  joined  in  this  extension.  Over  a  large  area  south  of 
the  railway,  however,  no  remnants  of  these  early  glacial  deposits 
have  been  found.  They  were  probably  almost  entirely  removed 
during  the  long  interval  when  stream  erosion  was  going  on  or  were 
obscured  by  being  overrun  by  the  great  Two  Medicine  glacier  of  the 
Wisconsin  stage. 

In  places,  as,  for  instance,  on  the  ridge  north  of  Lower  Two  Medi¬ 
cine  Lake  and  on  St.  Mary  Ridge,  the  long  exposure  of  this  old  drift 


48 


GLACIERS  OF  GLACIER  NATIONAL 


J.  n.uxx, 


3  0112  072879023 


to  the  weather  has  resulted  in  the  limestone  pebbles  and  bowlder; 
being  removed  from  the  upper  part  by  solution  and  the  calcium  car 
bonate  being  carried  down  by  the  percolating  waters  and  deposite 
as  a  cement,  binding  the  lower  part  of  the  drift  into  a  hard  con 
glomerate. 

The  relatively  great  age  of  this  early  glacial  drift  may  be  inferred 
from  the  fact  that  even  those  tributaries  of  Milk  River  which  received 
none  of  the  mountain  water  have  cut  valleys  several  miles  in  widtf 
and  hundreds  of  feet  deep  below  the  horizon  of  the  former  high-level 
drift-covered  plains.  It  is  believed  that  St.  Mary  Valley  was  deep 
ened  at  least  S00  or  1,000  feet  during  the  interval  between  the  earlie 
and  the  Wisconsin  stages  of  glaciation,  that  the  tributary  mountai 
gorges  and  other  valleys  were  correspondingly  eroded,  and  that  a| 
considerable  part  of  the  sculpturing  of  the  great  mountain  mass  wa 
accomplished  during  this  period  of  stream  activity.  Compared  wit 
the  time  which  has  elapsed  since  the  Wisconsin  stage  of  glaciatio 
the  interval  of  deglaciation  must  have  been  very  long. 

In  the  above  discussion  the  pre- Wisconsin  interval  has  bee 
referred  to  as  a  single  uninterrupted  epoch  of  deglaciation  and  ero 
sion.  There  is,  however,  definite  evidence  that  it  was  not  such 
There  are,  east  of  the  mountains  in  the  Blackfeet  Indian  Reservation 
remnants  of  three  sets  of  plains  above  the  levels  of  the  present  drain 
age  lines,  all  of  these  older  than  the  drift  of  the  Wisconsin  stage  o 
glaciation,  and  on  two  of  these  are  deposits  of  pre-Wisconsin  glacia 
drift.  The  third  set  of  these  plains  comprises  the  broad  valley  bot 
toms,  onto  which  the  glaciers  of  the  Wisconsin  stage  encroached  an 
into  which  the  present  streams  have  cut  their  sharp  narrow  channels 

It  is  thus  probable  that  there  were  two  distinct  earlier  stages  o 
glaciation  of  the  mountains  separated  from  each  other  and  from  th 
Wisconsin  stage  by  long  intervals  of  deglaciation  and  stream  erosion 
Some  of  these  stages  may  have  resulted  from  or  have  been  accom 
panied  by  general  elevation  or  depression  of  the  region. 

Within  the  limits  of  this  brief  paper  there  is  not  opportunity  t 
discuss  all  the  evidence  bearing  on  this  question.  For  furthe 
details  reference  should  be  made  to  other  papers  by  the  presen 
writer  and  others.1 


i  Pre-Wisconsin  glacial  drift  in  the  region  of  Glacier  National  Park,  Mont.,  by  Wm.  C.  Alden,  BullJ 
Geol.  Soc.  Am.,  vol.  23,  pp.  687-708,  1912. 

Ditto,  by  Wm.  C.  Alden  and  Eugene  Stebinger,  Bull.  Geol.  Soc.  Am.,  vol.  24,  pp.  529-572,  1913. 

The  Montana  lobe  of  the  Keewatin  ice  sheet,  by  F.  II.  II.  Calhoun,  Prof.  Paper  U.  S.  Geol.  Survey,  NoJ 
50,  1906. 


lip;? 


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